Most of the discussions I've seen about this disregard the fact that on paper it's all nice, but in practice it's a rabbit-hole of constraints. Developers often use 3rd party SDKs and services that can render the game useless if they are not included is just one concern, and many times they cannot be technically or legally included in client versions for players.
Personally, for all I care, even as a game-dev, I don't mind if there'd be a law that would allow players to modify and even reverse engineers previous versions of the game for the sole purpose of playing the game.
This kind of regulation demands nothing from the game developers, doesn't force them to comply with anything, and doesn't incur any additional costs. Maybe there'd be some tiny loss of revenue, but it's arguably miniscule if the games are already abandoned.
It pretty much already happening with games like the C&C Generals that have pirated abandonware versions.
Most of the demands I've seen from the SKG crowd demand actual laws that define what developers must provide players, instead they should just legalize reverse engineering.