> The US will have lost a lot of political goodwill by then

Not really. All Governments across the World have undergone similar crisis in their own Countries, in different points in time in their own history, and know well to differentiate an erratic Government from its populace. I bet no one has ill-will towards Americans (unless you are into terrorism) and so will obviously want to mend ways once a better admin is elected and put in place.

The issue really though is not about political goodwill. It is about business that gets moved elsewhere. Once moved, it is really hard to bring it back. So US will then have to make a lot of concessions when it comes to that. The reason rest of the World is upset with the new tariff regime is not because they are being affected by it monetarily (which they actually are not), but because they do not want to sever a well established system and go looking for new buyers/sellers. For example, China decided to stop buying soybeans from US (after Trump threatened tariffs) and switched to buying from Argentina. Now once a new US admin is in place, it will have to give a better deal for China to switch its already established supply chain with Argentina to US again. Inertia is a good thing in trade. Infact, I feel it is even more important than building a moat. People are willing to continue paying higher price (even if something cheap is available elsewhere) because they do not want to go through the hassle of moving away from already established supply-chains and renegotiate new deals.

> really unpopular measures to clean up the mess

Agreed.

> Once those are running there's no incentive to look at US ones again

They will if US comes with better deals. This is the "unpopular measures to clean up the mess" you were pointing to earlier. Right now there is a mismatch between what US is actually worth and what it is projecting. I am not saying it is not a superpower anymore. It still very much is. But it is failing to recognize the rise of great powers in the rest of the World. And is unable to reconcile with multi-polarity that has already arrived and exists. As long as US is in denial of this reality, it will continue to make mistakes.

> And any geopolitical influence that was lost will already have been filled by other players who will entrench themselves

I agree but I'll go further and argue that the Trump admin is behaving erratically because it has realized it has lost geopolitical influence and that other players have already entrenched themselves. Trump has diagnozed the problem correctly (that US has lost its hegemony in many areas) but has no expertise (or even experts around him) to advice him on the right course of action.