Boris's whole strategy was to force an early election, so he could campaign on a 'people vs parliament' platform, pitting himself, the valiant underdog representing the will of the people, against the corrupt old establisment who were trying to rush through a bill to prevent Brexit happening at all.
The problem with Boris (well, one of the problems), is that he's not the sort of person to have a plan B.
So now plan A has backfired dramatically because:
- Labour and other opposition parties were understandably unwilling to back an early election until the bill had gone through and the request for an extension approved, and the cliff-edge of 31 Oct removed. Particularly when everyone could see what Boris was trying to do, and his strategy was so transparently obvious
- Parliament were able to force the bill through against Boris' will. Helped in part I'm sure by the arrogance of Boris and Rees-Mogg alienating any Tories who might have stayed with them.
So this situation means that Boris has three new options:
- He can comply with the law and request an extension of the deadline. However his entire position has been that he will not do that under any circumstances, e.g. "I'd rather be dead in a ditch than delay Brexit".
- He can refuse to comply. Uncertain what the outcome would be, but likely prosecution as he'd be in contempt.
- He can sidestep the issue by resigning.
No idea which way he'll go. Resigning (or attempting a vote of no confidence in his own administration) is perhaps more likely than the other options. I can imagine him telling the nation that he'd tried to give them what they want, but evil parliament had forced him out and threatened to throw him in prison.
If he does resign, the most likely outcome then is I think that opposition parties plus Tory remainers and the 21 new ex-Tories form a short-term new government to remove the cliff-edge and then call an election.
So as far as I can see, the most likely outcome is that Brexit is delayed, again.
As to how an election would pan out, it's anyone's guess. Brexit has destroyed traditional party lines.