Come to think about any possible hard fork and splitting the chain like it happened many times in the past, you have to wonder, why are they shooting themselves in the foot?
Because if you have a substantial amount of hash rate to have any influence, why would you remove your self from the competition and allow other miners to benefit by replacing you?
Since you'd be moving to a new altcoin and would allocate your hash rate to mine the new coin, which will become more of a dead coin over time, you would be doing the rest of the miners a favor.
If they are ever going to do anything like this it will be to rewrite the rules for the network which will be beneficial for them. I think they have the money and if they have the hashrate then they just need support from most of the dev community to promote the new bitcoin network and deframe the old one. This is not an excuse for them to try but the point is are they interested in doing anything like this? The future will reveal the answer.
Chinese miners made a mistake by migrating some of their hashing power into alt/forks, it allowed US to take control of the majority of hash power.
And now if US miners decide to fork, it'd be a strategic mistake IMO. So I'd say there will be no forks, but US is known for such mistakes. That's why you should be ready for anything.
I agree with your statement but I think Chinese miners shifted their hashpower due to the unfavorable policy of their government towards bitcoin miners and those who didn't want to shift their mining power just relocated their base of operation to another country.