Well, I certainly agree that there'll be lots of political butterflies. Can't address everything you've said right now,
@WolfBear, but a few thoughts come to mind right off the bat:
The butterfly ballot certainly won't be designed in this TL, thus making it easier for Al Gore to win Florida in 2000 if Bush Jr. still has both that DUI revelation and "Social Security is not a federal program" gaffe several days before the election.
Footage of everything you describe is already on YouTube, as is, so odds are Bush and Gore will probably see it and — even assuming an unusually generous (if "selective") butterfly net — readjust their responses accordingly, if ATL 2000 ever comes down to that.
Even then, I doubt we'd have the same candidates running on quite the same issues, due to compounding butterflies being the more likely scenario to begin with. For one, I'm pretty sure Bush Jr. will be kissing whatever aspirations he had goodbye, once the train-wreck of his OTL presidency comes to light. At best, I think he'd be able to run for a local office after foreswearing his future self, assuming he at least made a decent Governor of Texas (which I'm not as familiar with).
I expect Donald Trump's popularity to significantly fall among the left and libertarians while significantly rising among the right, especially among the less-politically correct right, decades earlier than in real life. 1980 Trump is going to realize what pays off much earlier.
Definitely expect Eighties Trump to be taking notes here, though I'd dispute your point about his older self being terribly popular with downtimers.
Widespread agreement with his actual platform, I can entertain — especially when news of out-of-control immigration, the fall of the Rust Belt, and mass-outsourcing to China of all places makes the news and takes the American people by surprise. At the same time, I'm guessing the pollsters would file off the serial numbers first, given how his crude and pseudo-folksy boorishness contrasts starkly with the aged grace and grandfatherly eloquence of the GOP's current favorite.
If anything, I think Trump the Man would be a big red flag showing how American politics has degraded, though considering that he's clearly not the only one with "issues", I suspect most modern politicians would seem clownish and absurd to downtimer audiences. Having a black, orange, and now pasty-corpse president back-to-back-to-back will do that.
("Looking at you, Resident Biden!"
)
Maybe there are greater odds of immigration reform being achieved much earlier? The demographic situation was not as favorable for the far-left as it would subsequently become, and US public opinion was much more hostile towards increasing immigration in 1980 than it will be 40+ years later:
Hadn't seen these before, so thanks for the tipoff.
But yeah, I'd expect (mostly) bipartisan agreement that the US needs to impose tougher immigration laws preemptively, to prevent artificial demographic shifts or cheap foreign labor from flooding the domestic market. In fact,
while I'd expect him to be less "scolding" than Clinton was in his delivery, it wouldn't phase me much if President Carter made it an issue at the next State of the Union address, too.
This might actually be enough to kill the 1986 amnesty in the US in this TL.
Probably.
Also, correct me if I'm wrong, but I believe Reagan agreed reluctantly to an amnesty, in exchange for Congress — then controlled by Democrats — to give him some concession he never got? I believe it had something to do with lowering taxes, but maybe I'm misremembering on that.