[plopilop]

They are in the process of leaving. They activated article 50, which automatically starts a process of departure lasting 24 months. This period can only be prolonged by unanimity vote, I'm not even sure it can be cancelled. Concerning the prolongation, not going to happen.

Also there's no way the rest of EU is going to accept for UK to stay in the EU with the same privileges as previously (non use of euro, tax exemptions...). Especially since UK was one of the most critical members, now EU has more incentive to move forward.

Personally I can't see how UK can rejoin the EU without applying from scratch like Serbia and so on.

[NeedMoreTea]

No way to one of the largest net contributors of the EU budget? I wouldn't take that bet. Sure things in politics have a way of biting back.

It's vanishingly unlikely in the time remaining, but I would not be surprised to see huge amounts of flexibility magically appearing, if the UK somehow gained a different administration supporting remain or a second referendum. Even at this stage.

[plopilop]

Honestly, given how the negoctiations led by Michel Barnier on the EU side has been openly skeptical towards Brexit negociations, I doubt it.

[dagw]

I'm not even sure it can be cancelled.

Both Junker and Tusk have repeatedly stated that they'd be happy to cancel the Article 50 negotiations at any time and let the UK stay in the EU under its current terms.

[plopilop]

Yes but given that prolongations must be voted by unanimity, wouldn't be logical that cancellation should be, too? I really don't know if that would be attainable.