Your 'if tomorrows' presume Trump continuing in the presidency, so of course no one is going to trust what comes next from Trump.
I say other nations are and should be behaving as if The U.S. is at the very least not behaving as an ally though not yet acting as an adversary, save towards Ukraine.
No intelligently led nation will permanently shut the door on a country's whose post WWII, Cold War, alliance building, NATO supporting history is the polar opposite from the present rogue behavior of a corrupt inept president.