There is no "capture" here, it's trivial to switch LLM/providers, they all use OpenAI API. It's literally a URL change.
As the LLM developers continue to add unique features to their APIs, the shared API which is now OpenAI will only support the minimal common subset and many will probably deprecate the compatibility API. Devs will have to rely on SDKs to offer comptibility.
At least for now, LLM APIs are just JSONs with a bunch of prompts/responses in them and maybe some file URLs/IDs.
So? That's true for search as well, and yet Google has been top-dog for decades in spite of having worse results and a poorer interface than almost all of the competition.