Are you sure you're not mixing up companies training their own frontier-ish models with companies providing hosted LLM API? For a close comparison, VPS hosting provider market did not collapse to a small number of players - few companies dominate the market (AWS, GCP), but there are thousands (or tens of thousands) of medium and small players available.
And that isn't sustainable. The market will collapse into a small number of players, in exactly the same way that literally every other market has.
Are you sure you're not mixing up companies training their own frontier-ish models with companies providing hosted LLM API? For a close comparison, VPS hosting provider market did not collapse to a small number of players - few companies dominate the market (AWS, GCP), but there are thousands (or tens of thousands) of medium and small players available.