That’s one possibility; a different one is that Trump considers China as the real contender for the US in the 21st century, and wants to pivot the US attention there (and out of Europe.)
The US performs a two-fold security function in Europe: first, it protects Europe from extra-European threats. Second, it protects Europe from intra-European threats. If however the US exits Europe, both kinds of threats become a reality overnight. When you think of what Europe is going to do if faced with any of these situations, it becomes very clear that China has absolutely nothing to offer on either front.