I doubt that Steam will play a major role for games on Macs in the foreseeable future, although they are the only game selling platform I am aware of that does even sell macOS games. The starting point for gaming on Macs is Apple Arcade, and once Apple manages to guide Apple Arcade users to the Appstore for more game content, the latter will be dominant on Macs.

But never, ever will Mac outrun Windows as a gaming platform. Even a M1 Ultra will not be able to compete with most recent GPUs of Nvidia or AMD.

The M1 GPU has the power of an NVIDIA 1060, which isn't enough to play present games with just minimum settings. And as long as macOS has a market share of around 10% only in the PC market, developers won't prefer Macs for their games. Most will not even bother to port their games to that platform. Like it is today.

I am both a softwae developer and a gamer. Whereas my Mac is way more suitable for my business needs than a Windows PC, I play on PS5 and Windows, when I play. That hardware is or can be tuned for gaming without compromises. And it has all the games available, not only some.