I wouldn't predict, but I think Theresa may will pull the vote, because she is absolutely determined not to go.
She is hell-bent, not her own destruction, but on everybody else's because she is incapable of accepting that she is a disaster as a Prime Minister.
What I would like to see happen would be that she, Oliver Robbins and Philip Hammond (responsible for circulating all the disaster theories), superseded by a team of negotiators: Boris Johnson, David Davis and Dominic Raab, and a great deal of table thumping and slapping of papers, and an absolute refusal to leave until the deal WE want is negotiated.
But I can predict that won't happen.