How do you know that Steam will be around in 20 years?
Use GOG instead, since the DRM-free game installers will outlive Steam :)
How do you know Windows will keep compatibility in 20 years? Valve money partially goes into Proton/WINE development and an evolution of that will absolutely be around in 20 years, just WINE was around 20 years ago already. CD Project doesn’t put any GOG/Cyberpunk money into breaking the Windows monopoly. (Also plenty of titles on Steam come without DRM because DRM is optional.)
How do you know Windows will keep compatibility in 20 years? Valve money partially goes into Proton/WINE development and an evolution of that will absolutely be around in 20 years, just WINE was around 20 years ago already. CD Project doesn’t put any GOG/Cyberpunk money into breaking the Windows monopoly. (Also plenty of titles on Steam come without DRM because DRM is optional.)