It will take a generation for the reputation of the USA to be restored, even if we start right now.

You’re an optimist. I think we have lost a great deal of soft power that can never be regained. Because even if the next guy is normal, the citizens that decided this is what they wanted will continue to exist for decades after Trump is gone. There’s no reason for non-Americans to assume this is some kind of one-off anomaly and not a sea change in the culture of the US.