My tentative understanding is that the vote would probably be on The Deal (whatever that turns out to be) vs Remain.

Or perhaps The Deal, vs No Deal, vs Remain, with transferable votes.

A charitable interpretation of May's actions is that she set up Chequers as The Deal knowing it was impossible, which would leave Remain as the only possible result.

But that's more likely to be wishful thinking than reality.

Meanwhile rumours of a November election - possibly with a subtext of "This is your referendum" - are intensifying.

Of course, that could just be wishful thinking too.

In reality no one knows anything - including the people whose job it is to know things.