nostr:npub1jeqcnv0u9nyz8vjknegr2p62f54hfm3v9srudwq4rzarz4tqwk7qlujglm the Steam Machines lack of commercial success doesn't invalidate the time they played in the development of the SteamDeck. In fact, it was one of the driving factors behind the redoubled investment of Valve in Wine/Proton development to improve DirectX support.
As for the API transition, I don't think anyone actually expects it to happen overnight.