It might not seem like the case right now, but I think the real disruption is just about to begin. OpenAI does not have in its DNA to win, they're too short-sighted and reactive. Big techs will have incredible distribution power but a real disruptor must be brewing somewhere unnoticed, for now.
Any other outcome would have split OpenAI quite dramatically and put them back massively.
Big assumption to say 'effectively controlled by Microsoft' when Microsoft might have been quite happy for the other option and for them to poach a lot of staff.