ChatGPT doesn't really have much of a moat. If it becomes Microsoft or Nvidia exclusive, it just opens an opportunity for its competitors. I barely notice which LLM I'm using unless it's something super specific where one is known to be stronger.
I'm pretty sure they'd like to keep selling chips to all of OpenAI's competitors too.
Chatgpt is not the only game in town. Any exclusivity deal will likely backfire against chatgpt.