My prediction is that the remoaners, while being undemocratic whiners, actually needn't worry too much, as there are lots of very rich, corrupt and powerful forces on their side.
Starmer will probably be the next PM. He may well sign us up to some sort of very obedient trade treaty with the EU, supposedly just to solve a few issues, possibly even involving giving them some cash every year. Then, just as has always happened, this will evolve like a cancerous tumour and eventually become EU membership in all but name.
This has been the story of the EU all along - it started as a trading club then quietly evolved, is still evolving and will not stop until it directly rules over all of Europe's people with an iron fist.