This is the smallest obstacle, IMO. You could get rid of (or leave a small dual boot partition of) Windows, and use one of the good Linux distros tailored to a Steam OS-like experience, like Chimera or Bazzite, and just keep ticking along without missing a beat.
I love my Deck, but I'm already researching the process of eventually transitioning off of it simply because the screen is too tiny for my 40s eyes, and I don't get to use it handheld as much as I'd like. This upcoming wave of Deck-like handhelds with 9 and 10 inch screens will be looking very good in this upcoming year.
Maybe not a failure of a device, as us enthusiasts would probably still be able to make something cool of it. A failure of a product, definitely, as it probably wouldn't be successful enough with the casual user for the manufacturer to support it for long.