There's a voluminous amount of code and documentation on how to build and run LLMs. You can build your own chatgpt literally in a weekend and run it on a home server, based on publicly available models.
If OpenAI and Anthropic literally evaporated overnight, there would still be Chinese labs training and releasing new models.
I'm sorry - but you're not going to ban AI no more than you can ban the transistor. You could limit & limit the potential of who uses it - but historically that seems to benefit the few rather than the many.
Banning doesn't mean the thing you ban disappears, you're stretching the definition quite a lot. The limit you're talking about is what a ban is. I would personally support a complete ban on AI technology impersonating humans. At no point would I expect that would completely get rid of the phenomenon. But it should be seen as extremely cringe and face meaningful push back, given how antisocial and antihuman that is.
And then hope nothing else ever evolves intelligence.