One thing I see as underestimated is that having a major standard device is huge for indie development and could greatly benefit the most flourishing artistic landscape.
One of the problems today is that the indie and AAA markets are increasingly distant, publishing a game on the PS5 or XSX digital store is prohibitive for a small indie team, but if Steam Machine is successful, we can expect more easy access to indie games by (ex)console gamers, and later a reduction in publishing costs on consoles.
I believe Steam Deck has already started this process, but with a device that will compete with the 9th generation of home consoles the indie game diffusion could accelerate.
I think Steam already presents a large enough market to be enticing for indie devs.
A quick check shows that Steam likely has more monthly active users than Xbox, PS5, or Nintendo. I’m sure a large portion of those groups overlap too. So indie devs are likely to develop for PC first.
While I’m excited for what they just announced, I don’t think it will significantly change these numbers.