This basically boils down to “read the terms & conditions”, which isn’t unreasonable.
If a game states in its terms that access may be revoked at any time and you buy the game, then you have no reason to be surprised when access is eventually revoked.
Obviously when terms aren’t clear enough or intentionally obfuscated, that’s indeed an issue for legislation to act upon.
Then just pretend it doesn’t exist. I don’t understand how this affects the GOG userbase. All that happens is people speculate about how GOG is out to kill DRM-freedom.