U.S. charges Julian Assange under Espionage Act

Sadly i can see Trump extracting Assange when extradition on legal grounds wont work.

Trump does not care for most other countries then the US or international legislation. The question is more which country he would have Assange extracted from.
Given that Brittain was more then an Ally in the Coalition of the willing (iraq war) and is part of the 5 Eyes thingy i could be a greater deal for him.
Sweden would be more of a f* you towards Europe but could have at least to his mind less repurcussions.