It's 'sustainable' because there's enough regulatory risk to using Chinese models that many will avoid them, and a 3T parameter model is still a bit beyond even many enthusiasts for running locally.

That regulatory risk argument won't work forever. It's the same with how the US bans chinese EVs which is why Tesla has high market share in the US, but in the rest of the world, chinese EVs are doing big numbers. The future is going to be full of surprises.

There are US companies hosting the open weight models in US data centers.