The goal is a good one, but it's too specific. It should not be allowed for a developer or device manufacturer to kill or nerf any product remotely, once it was bought and paid for. This problem is sneaking into other non-game software, and even physical devices! If you buy a thing you shouldn't need to tether that thing to the manufacturer, and it shouldn't be possible to make it useless when they decide to turn dow…
I think we need to stop treating it as a dichotomy.
There's an understanding it won't last forever, when you buy a multiplayer game, ans making devs make offline versions in the cases where its trivial is going to bite indie game studios.
Gamers have repeatedly shown they dont like subs. Its hard to model "we want to charge you 40 cents per month, escalating with inflation" but thats what youre asking for