What would stop Huawei just cloning CUDA, making Nvidia irrelevant in China?

The main power of Nvidia is CUDA, not that much the hardware. Other companies are behind the GPU game because theirs isn’t that efficient, and they can’t use CUDA because it’s Nvidias intellectual property.

If the the trade war completely isolates USA from China, and it won’t be China’s interest to not be an enemy to the USA, they could just steal the API, clone it, and what’s the worst the USA could do? Not make any business with them? Already done. Afraid of USA suing them? So what?

It feels like USA thinks China needs them more than they needing China, but it seems like China would be just fine. They do things their own way, and more independent.

Is this a risk, or there’s something I overlooked?