Well, agreements aren’t worth the paper they’re written on if you can’t enforce them when push comes to shove. I agree that the US is less interested in meddling in every affair all over the world, but it’s a mistake to think that they’re not interested in maintaining hegemony and their status as the pre-eminent superpower. That’s the whole reason for the pivot to Asia, and both the Dems and Republicans are in agreement there: The goal is to contain China.
There certainly is doubt. The population is already declining and the economy has been growing far slower, as of late, than it should. The US also has more powerful allies, we’ll see how much damage Trump will afflict on that front. China’s ascent seemed certain a decade ago, now it is doubtful.