Google, Meta and Microsoft would have to compete on demand, i.e. users of the chat product. Not saying they won't manage, but I don't think the competition is about ad tech infrastructure as much as it is about eyeballs.
It might take Microsoft's Bing share, but Google and Meta pioneered the application of slot machine variable-reward mechanics to Facebook, Instagram and Youtube, so it would take a lot more than competing on demand to challenge them.