I mean they sorta already are? Xi Jinpeng was calling Vladimir Putin his "closest, most dearest friend" just a month or two ago. They already oppose the US (along with Russia) on every major international issue.
Why would anyone care what state heads say (this includes Trump and his comments about NK)? It means nothing and has no consequence...except maybe preventing fickle market fluctuation. You never hear "I hate this guy" because it's just pablum. Convince me otherwise.
I really don't understand why you would cite that as something meaningful.
Of course, Russia and China have attempted to unite vs. U.S. interests before, and it always turns out that they have more to disagree/argue about than they have to agree on. But it doesn't mean that it's not worth mentioning.