> Developers often use 3rd party SDKs and services that can render the game useless if they are not included
That is indeed a case, and potential solutions has been discussed. The main idea is that games that have already been made do not need to comply with this, so they don't need to change anything. Moreover, some videogames have already been released with middleware stripped out of them. From the top of my head: Doom 3, Blietzkrieg. So you can work around that.
> 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
To my knowledge, you can already do that in most jurisdictions. That's why there are a lot of decompilation projects that started in recent years.
> This kind of regulation demands nothing from the game developers
The problem is that for games with online components you also require server binaries, which you don't always have access to. So developers would need to provide at least those binaries. So unfortunately even in this case there will be something that developers must do.
> C&C Generals
That's a good example because EA made source code available last year for most C&C games. So people have been improving unofficial versions.
> Most of the demands I've seen from the SKG crowd demand actual laws that define what developers must provide players
SKG itself does not demand anything specific, that's the idea. People who support the initiative do provide some potential options, but I don't think they are forcing it on anyone.