SwingsitlikeHogan
Major Champion
I think that if Boris was to lose his seat he would remain as Tory leader and a candidate in a safe seat would be encouraged to stand aside, possibly by moving them up to the House of Lords, and Boris would then stand in that seat in a by-election.
...or they might seize the opportunity to 'dump the toxic' and look for a leader more able to appeal across the political divides (plural). But that is only my fantasy land.