I've seen the airplane/railway comparison a lot and I'm not sure I buy it.

Nvidia is currently important to training new LLMs but it's not that important to running inference on existing ones.

I think email might be a better comparison? If LLMs really do become something that everyone uses without thinking about (and at least anecdotally it's the first tech trend I've seen that all my non tech friends are using) then yes sure you can easily change provider but in reality most people are just going to use whoever wins, just like most people use Gmail.

So investors are putting in huge amounts of money to have part of the next Gmail, and many of them will lose but there will probably be some dominant player and sure you can change but once you've used one for a few years and it is as good as or equal to another, and it approximates to free, then you'll probably stick with it, compatible api and interface or not.