That said, Trump is far more interested in US domestic policy than foreign affairs. Almost all of his demagoguery has been about what he would do within the borders of the USA. His foreign policy statements are few and far between but he seems to be an isolationist which for the rest of the world would be a blessing. Stupid & uninvolved would be better for the world at a macro level than stupid and on a global rampage. We lived through that one after 9/11.
I have to agree with you there. The US has consistently failed, horribly failed, at "nation building" since post-WW2. There's just no more MacArthur's and the like with the foresight, authority, influence, and knowledge to help rebuild a country that's in tatters or that's gone through tremendous upheaval (like Libya, or Iraq. Afghanistan has been in pretty continuous upheaval for like 150+ years).
I'd argue the last half-century has been one after another variation of "Let's bomb the shit out of this place (or neighbor), stir up the pot, support a horrible human being to somehow magically turn a 3rd world country into a mini-US w/o infrastructure, proper wages to preclude bribery, or efficiency, then step aside and wonder aloud why that country looks as bad as it did before we spent trillions of dollars."
Trump will more likely just mess up the US. Sure, that affects many other countries in this global economy, but it'll be easier for them to adapt and just avoid that crazy middle brother of Mexico and Canada.