My informed guess for the liklihood of where we'll be on 1st of November is:
50% Brexit has been delayed to 31st Jan
45% Crashed into No Deal
5% Withdrawal agreement has squeaked through
So I suppose to answer your question, I think there is a 50/50 chance we'll have left by 31st Oct.
(At this point my favoured options is the WA getting through, because all else is very high stakes. But I don't see how it could, at this point, under this sorry excuse for a PM.)