You make two assumptions: 1. That Johnson means what he says. His final calculation on a deal or not will be this: does this win me an election. 2. That MPs and the opposition, despite their piss and bluster, think they can win a brexit GE. They can’t. Labour want and need an election about ‘what now’
Finally, ’the Prize’ for the HoC has always been ‘frictionless trade with the EU’. In other words remain part of the bloc and accept the rules. Any deal which offers this will, given the alternatives, attract support from MPs across the parties
I dunno you seem to be making a lot of assumptions as well. Firstly that any "brexit election" as you call it would be a walk in the park for the tories and a large majority. I don't see it as clearly as that by any means.