Yes.
About 15 minutes after the next president takes office.
I don't think so. Our "allies" have now learned that America is only as trustworthy as the whims of its benighted electorate. Even if our next administration should inspire more trust, they will not forget how quickly they can be betrayed in another four or eight years.
I think the damage to American credibility is permanent.
Have you noticed that the electorate has changed dramatically in recent years? For whatever reason, folks escape 3rd World hellholes, come here, are granted citizenship, then vote for the candidate most likely to remake the USA into a carbon copy of the hellhole they left. Go figure.