He has been described as everything from Messianic visionary to terrorist, courageous battler for government accountability to sexual abuser. So why not chatshow host? That is the latest surprise incarnation announced by Julian Assange, who last week revealed his next step, after 13 months on bail fighting extradition to Sweden over sex assault accusations, would be to host a series of televised interviews with "iconoclasts, visionaries and power insiders" on the theme the world tomorrow". The series, beginning in mid-March, will comprise 10 weekly, 30-minute episodes to be screened on Russia Today, the Kremlin-controlled propaganda channel of the Russian government.

Whether the series is being pre-recorded is unclear, but as Assange knows, his next step – including where he will find himself in the next couple of months – is even less certain. On Wednesday , 421 days after he was arrested in London concerning sex assault allegations made by two Swedish women, the Australian will reach the final stage in his battle to avoid extradition to Stockholm to fight potential charges, when his case comes before the supreme court. And so his lengthy, surreal period of house arrest in a Norfolk mansion while fighting off, he recently revealed, the attention of the "hundreds" of besotted women who have turned up at his door, is coming to an end.

In February last year, a court ruled that Assange should be sent to Sweden to answer the accusations; he appealed, and lost. But two high court judges granted him leave to appeal to the highest British court, not on the circumstances of his own case but on a point of law: namely, whether a prosecutor had sufficient authority to require someone's extradition, as in Assange's case. Many legal observers were surprised when the supreme court not only agreed to hear Assange's petition, but said seven judges, rather than the usual five, would preside, "given the great public importance of the issue raised". The court will sit for two days, on 1 and 2 February, though the judges are unlikely to deliver their written verdict for a number of weeks.

Vaughan Smith, who has hosted Assange at his stately home, Ellingham Hall, for much of the past year on bail (Assange moved out shortly before Christmas), said the WikiLeaks founder views the supreme court decision as a "vindication" of his decision to fight extradition. "He felt if he was facing seven judges, clearly he had brought up a matter of public importance and, as a consequence, might argue that what he was doing had an element of public service about it."

But Julian Knowles QC, a barrister specialising in extradition law based at Matrix Chambers, said the decision to might be more easily explained by the enormous public interest in Assange's case – "to send the message that the highest court in the land has looked at this case, and it's had the attention of the best legal minds in the country".

Flexible

In Knowles's view, the law in this area – whether a public prosecutor is a valid judicial authority – has been comprehensively tested. "This point has been litigated before, and the courts have always reached the clear answer that while it may look odd to English eyes, common law eyes ... European systems don't have the same structure. The courts have always said that to make extradition work, you have to be flexible in your approach to what extradition is." The consequences if Assange were to win, he said, would be "very profound". "It would basically mean, until the law is rewritten, that extradition to Europe [would] become very difficult, if not impossible. Because in the vast majority of European extradition requests, the arrest warrant is issued not by a court, as it would be in England, but by a prosecutor."

It is much easier to predict what will happen if Assange loses. Though he would still have the option to make an application to the European court of human rights (as he has hinted he may do at earlier stages of the process), this would not delay his extradition, since Sweden is also a signatory to that convention. Instead, the extradition unit at Scotland Yard would agree with their Swedish counterparts a date, within 10 days, for Assange to be handed over, according to Knowles. The Australian would be required to present himself at one of the main London airports, where he would be handed to Swedish police, who would escort him on a flight to Stockholm. Once on Swedish soil, he would immediately be arrested.

In preparation for such an eventuality, Assange some months ago contracted new Swedish lawyers and a PR consultant, Harald Ullman, charged with restoring his reputation, which some claim has been "smeared" by supporters of the two alleged victims (the women's supporters, however, argue that it is they who have been unjustly characterised).

According to Per E Samuelson, one of Assange's new lawyers: "Bail does not exist in Sweden. We will of course try to get him released while awaiting the court case to take place. But ... normally it is not unusual that people are kept in custody in sex abuse cases before the court case has taken place. It is possible, he said, that Assange could be barred from communicating with anyone other than his lawyers in that period. "That is a matter for the Swedish court."

Dependent on whether sufficient evidence were found to bring an indictment, Samuelson said, that stage of the process might take three months. If an indictment were brought, the likelihood is that a trial would follow only a few weeks later.

Swedish rape and sexual assault cases are heard substantially in private, ostensibly to protect both the name of the alleged victim and the accused. That would apply in this case, even though Assange's name was leaked by police to Swedish media soon after accusations were made, while the women's identities have been widely circulated online by his supporters.

The trial, likely to take five to seven days, according to Samuelson, would be heard in a district court, which would deliver its verdict two to three weeks later. Both parties would have the opportunity to appeal.

Samuelson is clear in his position: "I know the case very well, and I would say that the accusations against him are a joke. He is quite innocent in my deepest belief." He also argues that "it is a bad climate to be accused of sex allegations in Sweden, because of the political pressure to convict, even if the evidence is weak. There is a political opinion that you should rely on the women."

Ingela Hessius, a Stockholm barrister who worked for 19 years as a prosecutor specialising in sexual violence cases, declined to discuss the particulars of the Assange case, but said she "strongly rejected" the characterisation of the Swedish legal system as a climate that favours women. "It has increased, the number of reports from people being raped, but the number of convictions is not very high, and the number of indictments is also not very high," she said. "There is something in the nature of the crime itself that makes [prosecution] very difficult, because you need something more than just the victim's story, otherwise you have version against version. That's not enough for a conviction, it's not enough for an indictment either. You need something more."

If anything, she says, "I think the courts are sometimes a bit afraid to convict in a sexual crimes case. So no, it is not a paradise for feminists at all."

Whether or not the supreme court rules Assange should face a Swedish investigation, this is far from the only legal process the WikiLeaks founder fears. The US government is prosecuting an army private, Bradley Manning, alleging he is the source of many of WikiLeaks's high-profile releases; it has also opened a grand jury investigation with the purpose of deciding whether to prosecute WikiLeaks or its founder. That process is carried out in secret, without any rights of access for Assange or his lawyers. Many of the Australian's supporters fear the US will seek his extradition – from the UK, Sweden or elsewhere – with a view to prosecuting him for "conspiracy to commit espionage", based on a notional allegation that he may have "coached" Manning to leak documents to the site.

David Coombs, Manning's lawyer, said at a preliminary court martial hearing in December that he believed the US military was attempting to strongarm the young soldier into taking a plea bargain and incriminating Assange, suggesting the WikiLeaks founder was regarded by the US as the bigger prize. Assange and WikiLeaks were represented at the hearing by Amy Jacobsen, a lawyer for the Centre for Constitutional Rights, a New York-based legal organisation focusing on civil rights, which has recently worked in support of Guantánamo detainees. She was denied access, despite the centre's argument that "the proceedings are clearly closely linked to a grand jury in Virginia reported to be issuing subpoenas for information on our clients".

Conspiracy

Michael Ratner, president emeritus of the CCR, told the Guardian he believed the grand jury was being used as a "fishing expedition" in the Assange case. The US department of justice never comments on grand jury investigations – indeed, their existence is known only if witnesses who have been subpoenaed to give evidence choose to speak of their experiences, as they are permitted to do. Does Ratner believe the US government is likely to seek Assange's extradition on potential conspiracy charges? "My hope is there is still a fight within the government, which says: 'How do you go after Julian Assange and WikiLeaks without going after the New York Times?' And I would hope that the voices of reason win out, but we have a lot of 'dark side' in our country. Certainly if you look at ... what they have done to Bradley Manning, it looks to me like they are by hook or crook trying to go after WikiLeaks and Julian Assange."

Though Assange and his supporters say extradition to Sweden would make such a process easier, Knowles disagrees. If Assange were to be sent to Sweden, he said, "the US can ask for his extradition, but they then have to do two things: they have to gain his extradition under Swedish law, and Sweden would also have to get the permission of the UK to send him onwards [since] if the UK sends anybody abroad, they can't be sent then to a further country without the UK's permission. So it makes it harder for the US, having waited all this time." In addition, he said: "If the US were to make an extradition request based upon his activities as a journalist, then it becomes immensely difficult legally," arguing the potential clash between allegations of espionage under US law, Assange's freedom of expression rights under Article 10 of the European convention, and the US first amendment rights guaranteeing freedom of speech, would present "a very complicated legal situation, the answer to which I wouldn't like to predict".

Any attempted prosecution for journalistic activities would almost certainly rouse a spirited international media campaign in defence of Assange. Alan Rusbridger, the Guardian's editor-in-chief, has said: "If, God forbid, this came to court, I would be completely side-by-side with him in terms of defending him with respect to what he did." Bill Keller, then editor of the New York Times, concurred.

As for Assange's Australian citizenship, it is unclear whether, or how forcefully, his government might seek to resist any possible US extradition attempt. Though three former prime ministers — Malcolm Fraser, Kevin Rudd and John Howard — have at different times spoken in support of Assange, Robert McClelland, Australia's then attorney general, indicated in December that the government would be unlikely to intervene in any potential US extradition request to Sweden.

For all the speculation over potential legal processes, there is, of course, a potential version of events in which the supreme court rules in Assange's favour, the US is unable or chooses not to indict him, and he finds himself, for the first time in more than a year, a free man. What might he choose to do then?

WikiLeaks has, it admits, suspended its activities at least for the time being, thanks to a financial blockade of donations, which Assange has argued has cost the site up to €50m (£42m). But while the choice of some of his new allies has attracted fierce criticism – his decision to broadcast on Russia Today, which silences any criticism of the Putin regime, has been condemned – he is not without powerful and wealthy friends around the world.

The Australian's UK visa expired during his time in custody — he has, in any case, surrendered his passport to police. But it is likely that he might, as a free man, seek to take his activities elsewhere. Asked in a recent Rolling Stone interview what he hoped to do next, Assange said: "I don't want to end up anywhere. I want to do what I was doing before. I lived in Egypt when we had important things that needed to be done, or in Kenya or the US or Australia or Sweden or Germany. When we have opportunities, that's where I am."

• This article was amended to reinforce Robert McClelland's status as attorney general at the time he commented on the Assange extradition issue in December 2011.