It’s as though a meteorite like the one that destroyed the dinosaurs has landed in our midst. Overnight, Brexit has gone from dominating British politics to suffering a form of political extinction. When the electoral meteorite hit on 12 December, Brexit became the issue that no one – not even Boris Johnson – wants to mention any more. In some ways it is a huge relief, not least to political commentators.

We all need to heal our wounds. So does the country. But while the essential issue has been settled, the conspiracy of silence that has followed needs to end. The UK needs to learn to think about Brexit again.

Regulatory and trade issues are all still to play for, and that must be done in public, with proper scrutiny

This is not a call to revive the passions of the recent past. Apart from anything else, that wouldn’t work. The intensity of those times is over. Neither the winners nor the losers in the Brexit wars have any appetite for reviving it. But Brexit must still be tackled, albeit in a changed way. Ignoring it would be a failure of democracy.

Next week’s official departure from the European Union will not “get Brexit done”. The UK will cease to be an EU member state. Some will celebrate that. Others will mourn. Politicians will issue their statements and journalists will report them. But this is the end of the beginning, no more.

The real challenge in the coming weeks and months is to get Brexit back on the agenda in a series of new ways. This means recognising and acknowledging that Brexit remains at the very centre of political and policy decision-making, not as an issue that must be refought from first principles as it was in 2016-19, but as a fact that will permeate almost every important policy choice facing Britain in the years ahead.

The first of these new ways involves recognising that the Brexit process will itself generate more big choices, not fewer. Johnson’s victory in December effectively solves the withdrawal itself. Even so, the bill that enacts withdrawal has been controversial because it reneges on pre-election Brexit commitments on issues including the role of parliament, employment rights and refugee children. None of these is a minor issue. The government has been smart and lucky to drive this bill through so quickly.

Yet the withdrawal bill says nothing about what happens next on Brexit. These regulatory and trade issues are all still to play for, and that must be done in public, with proper scrutiny. All this will come to a head, but will not be resolved, in June. That’s when Johnson must decide whether to extend the transition period beyond the end of this year. He is determined to avoid doing so because he wants to frame Brexit as finished business. But he also wants a deal with the EU. Sajid Javid said yesterday that an EU deal is more of a priority than one with the US. This makes June a crossroads moment for Brexit and Johnson.

The act of leaving the EU also sees the government face a series of big domestic decisions that cannot be put off, especially if the 31 December deadline for completing the transition is to hold. These include things such as immigration policy, regulatory policy over sectors such as financial services, the future of agriculture and fishing, and the place of human rights in Brexit Britain. Perhaps most explosively of all, the government must handle the post-Brexit pressures on the UK union itself, from Northern Ireland and Scotland in particular but from Wales and the English regions too.

On all of these major issues, Johnson faces formidable dilemmas. He has to deliver agreements, maintain confidence, keep his leaver base happy and avoid needlessly provoking all those whose support he may need in other contexts. He has to juggle party, economic, local and international interests in each case, while at the same time coping with the unexpected. Everything is shot through with Brexit, whether he likes it or not.

Yesterday, the Davos conference showcased a classic example of Brexit’s complex but irresistible continuing impact throughout British politics. The UK is under pressure from the EU and the OECD (Organisation for Economic Co-operation and Development) to defer its planned digital services tax on US tech giants so that policy-makers can hammer out a watertight international system of controls. France has already done the same this week.

The political problem is that the Johnson government’s priority is to live up to its own take-back-control rhetoric. It can’t work alongside the EU to achieve an effective regime against the lawless tech companies because the UK is supposed to be making its own decisions now. But it can’t back down on the UK tech tax because Britain doesn’t want to be seen to be bending the knee to Donald Trump. As a result, Johnson has been pushed into a position in which he both invites US retaliation and uncouples from the EU.

Brexit wasn’t meant to look like this. The row about the digital services tax is merely one among multiple others that require the Johnson government to make vital choices about where its real interests lie. Johnson’s stances on Huawei and on relations with Iran can only be understood in the same light too. On the domestic front, so can the indecision about the HS2 high speed rail project,, the future of Heathrow or the shape of Sajid Javid’s March budget. All of these involve choices that will strain the Tory party.

But the link between Brexit and these real-world choices can’t be ignored by other political parties either. That’s not a problem for opposition parties that are still confident in their anti-Brexit stances, such as the SNP. But it’s a real problem for Labour. Whoever its new leader may be, Labour urgently needs to fashion both a post-Brexit Europe policy and a narrative about Britain and Brexit. At the moment it has neither.

A metaphorical meteorite may have landed in our politics last month. But the dust is now clearing. Life must resume in these chastened surroundings. And so must the debate about the UK’s place in the world and about the kind of country it should be.

• Martin Kettle is a Guardian columnist

• This article was amended on 23 January 2020 because an earlier version referred to meteors, when meteorites were meant. This has been corrected.