If things got bad enough, I think he'd probably be as electable as any other Republican. The Dixiecrat wing of the GOP would probably find some reason to conclude "He's one of the good ones"(to quote Archie Bunker)
One problem might be that he's more directly identified with the social-conservatives, which might activate the liberal vote and get more otherwise stay-at-home Democrats to the polls. (Though if Trump wasn't enough to do that, ya gotta wonder if anyone could be.)