Unstoppable monopoly will be extremely hard to pull off given the number of quality open (weights) alternatives.
I only use LLMs through OpenRouter and switch somewhat randomly between frontier models; they each have some amount of personality but I wouldn't mind much if half of them disappeared overnight, as long as the other half remained available.
This is saying we have hundreds of open source OSes and Windows will never be a monopoly.
Software always gets monopoly simply by usage. Every time a model gets used by esoteric use cases, it gets more training data (that a decentralized open weight model doesn't get) and it starts developing its moat.
OpenRouter falls in the acceptable use category. They targeting users that are misusing their Claude OAuth token on non-Anthropic products.
They will [try to] ban open weights for ethics / security reasons: to stop spammers, to protect children, to stop fascism, to defend minorities. Take your pick; it won't matter why, it will only matter which media case can they thrust in the spotlight first.
I'm old, so I remember saying the same thing about Google and search.
I hope you're right!