I don't care about the US being a powerful country. I'm tired of being the world's police. I'm against so-called "American imperialism". I want to be Switzerland. Ally with no one, trade with everyone. Switzerland has a much healthier relationship with the rest of Europe, without toxic dependency.
That's my metric regarding whether an approach is "productive" or not. Give it 10 years until the US/Europe relationship resets to the Switzerland/Europe relationship. That's the goal.
I'd say Trump has already succeeded by this metric in terms of Europe taking responsibility for itself. That's the first step. You need to stop depending on us so you'll stop resenting us.