Given the strength of the Brexiters, with the weight of the Murdoch tabloids, the Tories would have to be beaten decisively, not by a small margin but a real sucker punch. And even then, we don't expect them to sit down meekly and say, oh well, we tried, now do we?

I too am skeptical about the "reformed EU" hypothesis (OK, OK, I'm French, so I'm skeptical by definition, but bear with me for a second): any reform in the EU is a long and glacial process that takes years and involve plenty of compromises. The clock is ticking: in EU legislative time, we're practically at the eve of March 2019.

And even if most of the EU would prefer the UK to remain rather than facing the unknowns of Brexit, the goodwill to bend over backward to accommodate the British demands has seriously evaporated in the past two years. As you remarked above, the EU already did that with Cameron in February 2016, to no avail. For the Brexiters, the only good "reformed EU" is a "dead EU".

Yes the power inversion needed for that is as immense as it gets.

David and Goliath.

Apart from 5* there isn't any other European political party who would be supportive of such change, or is there? Bernie Sanders, if he had been elected woukd have been enormous help to support Corbyn as they are cut from such similar cloth, but that doesn't look like it's in the immediate offing.

The people would be behind it, if only because everything else but outright fascism has been tried. (And because the majority of Europeans are sufficiently educated in history not to want to go down that road again, Hungary, Poland and Ukraine notwithstanding.) The forces of corporate militarism are strong in the North East and East of Europe, and socioeconomic solutions to poverty and lack of development, while an improvement on the iron curtain days, are still a source of rage, envy and frustration, rendering underemployed youth easy prey for simplist right wing nationalistic forces.
Just as you and Brit predicted ten years ago.

Brussels is long overdue for a fundamental shake-up. The democratic tools are still in place but there's a big shortage of leadership material, leaving us with the likes of Macron, May, Kurz et al.

Which begs the question is the EU necessary, let alone viable in its preset form? Is it still the primary preventive measure that will stop euro states squabbling to the point of repeating the darkest side of our history?

Can we afford top-heavy centrally planned economies of this scale and if so how can we make them serve the peoples' needs rather than those of the 1% as they are presently doing?

If Corbyn could make the EU more democratically accountable he would have earned his prime ministership.

'The history of public debt is full of irony. It rarely follows our ideas of order and justice.' Thomas Piketty