I don't think even if Trump were elected it would turn out catastrophically right then -- well, except maybe if he does something truly horrible with foreign policy (rather than "just" a worsening of war crimes or something like that) which is where he could do the easiest damage, I think, without running into your dysfunctional congress, that he is unlikely to get in a sweep with loyal allies, even if both chambers remained Republican majority, so he'd probably run into the same gridlock.

I think the even scarier part is that his electorate won't go away, but will get even more frustrated if they get disappointed by Trump as well, when he doesn't accomplish anything beyond angry posturing. And in the next iteration you may get the combination of all the implicit rules of civility boundaries being broken, people even more eager to dismantle the political system that failed them, and the formula is then used by someone who isn't a narcissist but a believer and is willing to cohere and build local movements and such.

I mean, from what I gather Cruz for example is all about some weird religious fundamentalist vision or something, but with the Trump example that some economic populism and protectionism talk combined with racism and xenophobia works better to attract people than being just all about the "war for Christian values" or whatever, but neoliberal Republican in economics, you get the next natural iteration of this, where the economic rhetoric switches.