I very much doubt that they will refuse to scan for whatever China asks. I very much doubt they'll risk the PRC shutting down Foxconn factories.
I very much doubt Apple will ultimately be able to resist scanning for whatever the US Government asks in a national security letter attached to a gag order. They will take them to a secret court session which we'll never hear about, the court will rule in the government's favor, and Apple will be forced to comply and not allowed to tell anybody.
This happened to Cloudflare and they were gagged while fighting it for 4 years. They didn't win in court, but the government eventually dropped the case as it was no longer needed. And this started under Obama, not Trump.
Now, will Apple bother to fight this out in court? I think they probably will. But we won't know about that until they either definitively win or the government gives up. If the government wins, on the other hand, we'll NEVER hear about it.