alt Hacker NewsValve's only official statement as far as I know is that it will come when they see a significant enough hardware upgrade to warrant a new system. If they don't move to ARM, AMD's Medusa APUs are their next architecture with major upgrades, so I would guess that Valve would order another custom AMD chip but based on Medusa, which won't release until at least 2027. I would guess at least H2 2027 but probably early 2028 for an AMD-based Steam Deck 2.
I would be surprised if they moved to ARM any time soon, because even if the CPUs can punch that hard, they're definitely not competing on the GPU front, from what I understand of the state of the art outside of Apple, so they're gonna wind up with a dGPU anyway if they did.
Maybe my knowledge is out of date, but I'd be kind of surprised if a Snapdragon can get anywhere near competing with even the existing Steam Deck on GPU performance. Looking at [1] for a ballpark number on Snapdragon GPU performance doesn't seem encouraging.
[1] - https://chipsandcheese.com/p/the-snapdragon-x-elites-adreno-...