Source is KeplerL2, who is generally considered a reliable source for insider hardware info, particularly on AMD GPU hardware and AMD SoC for consoles.
Previously I would have personally estimated Steam Deck 2 to release mid 2026-early 2027, but the recent info about an upcoming Steam Machine made me think that maybe I should push back that estimate.
Of course even if we assume this is reliable insider info, a lot can change in couple years, so things can definitely change.
The steam deck does benefit from common hardware. Valve will distribute prerendered shaders for the Deck’s GPU over steam game updates, so most of the time deck users don’t have to deal with shader stutter or wait for the game the render them itself during first startup.
Steam may share shaders between linux users with the same GPU, but I’m not sure. A new steam machine will definitely benefit from this though.