Honestly, if Valve gives their Steam Machines concept another go with their much improved compatibility and operating system, I think they may have an actual chance. They'll need to come up with a replacement for their terrible Steam controller that tried and failed to be a mouse, but if they just stick the two sides of the Deck together I think they're already almost there.
They'd also need to keep costs down like they do with the Deck and that's going to be a real challenge, but if they can get a controller + desktop out for about the price of the Deck but without the handheld performance restrictions, I think they can gain popularity.
Out of curiosity, did you personally actually use the steam controller? From what I've read/heard, it was a bit tough to get used to, but appreciated by many. My impression was also that the steam deck touch pads were just the next step in [the steam controller]'s evolution, rather than something else altogether.
All of that being said, I've unfortunately never had the opportunity to try it myself, so I don't really know.
I have one. I wanted to like it, but it just lacked. The feedback on the large directional buttons is limited, the controller isn't terribly comfortable to hold, and the ABXY buttons are at quite an awkward position. The trackpad to play PC games was an interesting idea, but it just didn't work for me because it lacked precision or range.
My biggest issue is that the touchpad lack precision that a normal joystick would provide, and you need quite some force to push the directional buttons underneath the DPAD.
It wasn't a complete design failure. I do miss the button on the end of the triggers, that was a smart choice. I find the Deck paddles a lot harder to press than the ones on the Steam controller.
The deck took everything the Steam controller tried to do and just did it better. The trackpads is still there, including the force feedback, but it's no longer used in place of usual controls.
With these lessons learned, I think Valve will be able to design an awesome controller!
They'd also need to keep costs down like they do with the Deck and that's going to be a real challenge, but if they can get a controller + desktop out for about the price of the Deck but without the handheld performance restrictions, I think they can gain popularity.