Given Trumps focus on vengeance against perceived enemies who have committed no crimes, enacting tariffs to punish other countries, and allying himself with dictators instead of traditional allies, I do not see the US remaining a global power for long. Already, the EU leaders have taken steps to reduce military reliance on the US. And with Gabbard as the Director of National Intelligence, the willingness of allies to share sensitive intelligence may disappear.
Trump will try to force Ukraine to give up Crimea and all Russian-occupied parts of Ukraine, but Im not sure the EU is ready to stop supporting Ukraine because they know it would only be a matter of time before Putin would attack again to take the rest of Ukraine and Poland would suddenly find Russian troops at its border.
The Middle East is a powder keg that Trump will most likely make worse. The US has already lost a lot of respect for its arming of Israels destruction of Gaza and the murders of thousands of civilians. Encouraging Netanyahu to finish eliminating all of Gazas population so settlers can move there would not go down well in most Arab nations, nor here in the US. What is happening in Syria just now has the potential to change the power structure in the Middle East, and I doubt anyone in Trumps orbit has a clue how to react. Ive never thought Rubio to be particularly bright, but perhaps he will be effective. Heaven knows he has to be better than Kushner, whose sole objective was building luxury condos and golf courses.