The European parliament’s vast blue and grey chamber is half empty when Nigel Farage gets to his feet. It is a routine debate on the EU budget and MEPs are not scrimping on detail. They have spoken of frameworks, roadmaps and sustainable goals. But that is not the Farage way.

Making a glancing reference to the “Brexit hole” in the EU budget, the former Ukip leader launches into an attack on Theresa May, who he says is “desperately scrambling” to get the UK into EU programmes, before segueing into a riff on Italy’s political crisis. A lone MEP, from Ukip, claps vigorously.

The two-minute speech is everything the others are not: brisk, punchy and almost completely irrelevant to the debate. But Farage is not addressing the EU budget commissioner, his true audience are the tens of thousands who will watch later on their computers or phones. Within 48 hours Farage’s speech has had more than 82,000 views on Ukip’s YouTube channel, while barely 1,400 people watched the debate on the EU’s broadcasting service.

By Ukip standards, these are modest figures. Videos of Farage telling one EU leader he had the “charisma of a damp rag”, or his post-Brexit referendum declaration to MEPs that “you are not laughing now”, have had millions of views.

But in March 2019 Farage’s monthly show in the European parliament will be switched off for good. The party’s 19 MEPs will leave the European parliament, losing generous salaries, expenses and EU funding that has boosted party fortunes, while also triggering investigations into misspending. In 2015 Ukip declared an income of £5.8m from members and donations in the UK, while Ukip-dominated groups in the European parliament received €5.4m (£4.7m) in EU funds, shared with other Eurosceptics.

Farage has always understood the importance of European elections, describing them as the “lifeblood” of Ukip in a 2014 lecture at the London School of Economics. “Without the European elections, without getting three seats in 1999, without getting the resources that the European parliament made available to us ... without the letters ‘MEP’ after our names, Ukip would never have appeared on Question Time, or Any Questions or any of the major media programmes in this country.”

Farage, who has the worst attendance record of all British MEPs, has been advancing his media career. “Talk radio is fun and it’s going to grow so I am going to enjoy that,” he told the Guardian.

But following a disastrous performance in the local elections that resulted in a 1% share of the vote, Ukip seems on the way to political irrelevance. In an attempt to look on the bright side, a senior party official compared the party with the Black Death. After going through four leaders in 18 months, members are uneasy about the fifth: the London MEP Gerard Batten, who wants to move the party to a hard-right anti-Islam position. His march in support of the far-right English Defence League founder, Tommy Robinson, prompted one MEP, James Carver, to quit the party and sit as an independent.

A march in support of far-right activist Tommy Robinson in June after his jailing for contempt of court. Photograph: Daniel Leal-Olivas/AFP/Getty Images

Batten’s approach has won support from some party veterans. John Stuart Agnew, one of Ukip’s longest-serving MEPs, says he would like to see the party confront what he calls “the problem of Islamification” and claims there is “a new political system coming in, something called sharia zones”. Agnew, a farmer, who represents the East of England, admits he has never seen a sharia zone, and bases his claim on a documentary he once saw, the name of which he cannot remember.

While he thinks there is nothing inevitable about the party’s survival – “it depends on our policies” – he singles out immigration and the NHS as Ukip issues. “There is still not a proper handle on immigration. I know that leaving the EU will help that but there are still large numbers of people coming in.”

Ukip has long been an unstable party, riven by in-fighting and scandal. Since 2014, seven MEPs have quit the party or the parliament, including the leader-for-18-days Diane James, the former leadership contender Steven Woolfe, who was hospitalised after an altercation with a Ukip MEP, and the former head of delegation Roger Helmer, who resigned as an MEP amid questions about the alleged misspending of £100,000 in EU funds.

The Labour MEP Richard Corbett thinks Ukip cannot survive on the same scale without EU support. “They have imploded as a party,” he says, noting it has also lost “substantial amounts of money”, after one MEP libelled and slandered Labour politicians. Corbett, who lost his seat to the BNP in 2009, attributes Ukip’s rise and fall to its charismatic leader. “If Farage had been leader of the BNP, we would be talking about a BNP problem, instead of a Ukip problem.”

Matthew Goodwin, a politics professor at Kent University, says it is too soon to write off Ukip or discount the emergence of a similar party able to mobilise the same voters. “Ukip has collapsed, but the last five years in British politics should warn all of us against assuming that there is no potential for populism going forward,” he said.

If the final Brexit deal does not deal “meaningfully” with reform of free movement of people, which leave voters expect, “then Ukip or more likely a party like the UK Independence party will probably emerge on Britain’s political landscape”, says Goodwin.

“If you are an average leave voter thinking that that leave vote gave you less immigration, you are likely to be very disappointed one, two, three years from now when you realise that what you got was not what you associated with Brexit, but something altogether different,” he says.

“I think 10 years from now, 20 years from now, we may come back and look at this period as possibly a moment of calm before another storm.”