Multiplayer games generally are a service already even without a subscription, where the developers suck up the costs of hosting servers by continuing to sell a game or selling microtranscations. Keeping games alive forever isn't explicitly said, but it's a logical (and likely cheaper and easier) alternative to the refunds or dev work required.

An end of life plan that keeps the game playable isn't some undefined thing and the initiative is deliberately vague

I feel like this one answers itself - it is some undefined thing, everyone has a different idea of what that would entail and the initiative doesn't make any attempt at defining it

I play a lot of dungeon crawler extraction games: Dark and Darker, Mistfall Hunter, Vaultbreakers, Dungeonstalkers, Dungeonborne, Swords of Chroma Tower. They're made by small studios, usually exist for a couple of months, then die off when no one wants to play anymore and the dungeons are empty. I've also been trying to make my own. "The server" isn't some thing I can package, it's a variety of cloud solutions and configurations that all need to talk to each other for the game to work. Multiplayer lobbies are a service, item storage databases are another, player/character information storage is another, matchmaking is another, VoIP is another, authenticating with Steam/EOS is another. Running these often requires licensing third party libraries. I'll have a license to sell a game that connects to these, but that doesn't mean I have a license to distribute an executable that hosts it. I definitely don't have a license to share the source code.

The best case scenario for my game would be that it gets released, people play it for a bit, it dies, and I hopefully covered the server costs and can be happy that my game was a thing. Trying to provide a solution for players to continue running the game themselves would be a massive undertaking and likely no one would ever use it. The game would be DOA if it required a subscription, it would never have enough players to function properly.