If you're writing an LSP for a language, you're implementing the necessaries according to the protocol (when to show errors, inlay hints, code fixes, etc.) - it's not deciding on its own.
My app has a simple drop down box where users can pick whatever LLM they want to to use (OpenAI, Perplexity, Gemini, Anthropic, Grok, etc)
However if they've done something worthy of putting into LangChain, then I do hope LangChain steals the idea and incorporates it so that all LLM apps can use it.
Lots of companies open source some of their internal code, then say it's "officially a protocol now" that anyone can use, and then no one else ever uses it.
If they have new "tools" that's great however, but only as long as they can be used in LangChain independent of any "new protocol".