I'm sure there was tons of external meddling in most of eastern Europe before the many regime changes. It's very hard to draw any comparison between 80s eastern Europe and today's Iran. I don't think you really fathom how ingrained the regime really is. First of all Iran is huge and very rich in resources which makes the regime very rich and iran is technically self sufficient with food and energy. second, the regime has evolved and learned from the mistakes if other regimes making sure to have large foreign armies that don't give a shit about the Iranian people as long as the money keeps flowing, i could go on.

Also you seem to not grasp that the current regime are viewed as invaders forcing Islamic rule which I'm pretty sure is very very different from the scenarios your mentioning. And even in your scenario, if Trump really succeeds in destroying American democracy and takes everyone's guns away and closes the internet to the world and starts killing every and all opposition and terrorizes America for 40 years I'm pretty sure you'd like who ever the duck is capable of removing that to intervene. And it's not like I'm making it up, i happen to have many Iranians in my family, and many of them living in Iran still and i can assure you that the vast majority in the big cities want the US to kill off the regime. I'm sure there's some kind of rural population that loves sharia like the us has maga, but i don't think they are the majority any more.