I'm not sure if it's really a "trump agenda". The ideas didn't start with him, the people who voted for said ideas aren't going to suddenly disappear, and this is his second term.
It looks more like part of the new normal from the outside, and that's why things are changing. A country can't go from reliable to unreliable partner every 4 years without any consequences.
Even the people that voted for Trump didn't sign up for this, which is why his approval ratings are terrible even by historic standards. He didn't run on a platform of "attack Canada and suck up to Putin". Most Americans are very pro-European. Most of the voting population has living memory of the cold war.
As to what happens post-Trump, it's anyone's guess. I expect a hard reset. Markets have short memories, as they say.
Not to the same extent, but during his first term, his administration had issues with Canada, Mexico, Europe/UK, NATO, China, etc. Tariffs were a thing back then already. And he was elected again. Clearly it wasn't a huge issue for those who are bothered to go out and vote.
In any case, for everyone else, it's the second time in 10 years that they have to play the waiting game until it's over. It's good to be optimistic, but when you're in charge of a country, you can't just plan for the best and rely on hope alone. Same if you run a company or and even with services you as individual use.
Regarding memories, I don't know about the markets, but in Europe I think it will take a few years for everyone to forget that in 2026 Denmark had to transfer blood reserves to Greenland and that different European countries deployed tripwire forces because of... the US of A. Do you know who triggers similar responses? Russia, when they start saying that their borders are fluid.
In two more, possibly less, the current administration will be gone. The Trump agenda will be dead in the water by the end of this year.
While I basically agree with you, I wonder how quickly people will forget.