The way I'm understanding it now, The UK is not probably not leaving on 31st, unless Boris is willing to go to jail over what he allegedly believes, (a situation he 50% got him self into really)
I'm 99% sure he will not be willing to do that :P, Nothing about the guy strikes me as remotely sincere. even when he's being honest he sounds like hes making it up ffs.
Ive read that one bizarre option that might be possible to him would be a vote of no confidence in himself, which could result in the Queen appointing Corbyn as PM.
That would actually be hilarious (in the short term anyway)! No doubt Corbyn would run to the EU to ask for an extension like a good boy, which they would almost certainly grant, and so the saga and the bickering would drag on....