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 personally hope you’re wrong again. I think the level of hype should provide a huge stack of orders early on, and I think SteamOS is now SO good that this could go to the moon after the honeymoon period.
Time will tell where between you and I it winds up.