Even Steam Deck is only a success, because it depends on Windows ecosystem, and the moment Microsoft decides it is enough, lets see how long it holds.
All the games that matter are Windows games running via Proton, as Valve has failed to actually build a GNU/Linux native games ecosystem, in spite of UNIX/POSIX underpinnings of Android NDK, PlayStation, the studios hardly bother.
The day Microsoft actually decides to challenge Proton, or do a netbooks move on handhelds with XBox OS/Windows, the SteamDeck will lose, just like the netboooks did.
Additionally, it is anyone's guess what will happen to Valve when Gabe steps down.
Everyone is quite curious what Microsoft will drop at CES 2025, and which OEMs will be on their side, it is going to be netbooks all over again.