Imagine a Steam TV with the Steam Box simply built-in. That would be incredibly nice. The worst part of my brand new LG G5 OLED TV is the software itself. I'd pay a good deal more to have Valve responsible for the software running on my TV.

It might be nice for a little while, but the PC component is going to age much more poorly than the display will.

I think the better move would be for Valve to make a really nice gamer-oriented dumb TV that's essentially a 50"+ monitor. Kind of like those BFGDs (Big Format Gaming Displays) sans the exorbitant prices. The size of a Steam Box is in comparison quite diminutive, so finding a place to put it shouldn't be too much of an issue and the ability to swap it out for a newer model with the same screen 5+ years down the road would be nice.

There's actually a quasi-standard of TV-compute unit interface made for industrial displays. This could be really nice for things like steam cards that could just slot into TVs with whatever performance you need.

https://youtu.be/q9a3dCd1SQI

And even better make it as open as Steam Deck/Machine and allow to install any GNU/Linux distribution onto it maybe even something with KDE Plasma Bigscreen or something similar if desired.

You can get TVs with a "PC slot" like the Sharp M431-2. Just need a Steam Slot.