Nobody can be forced to keep supporting their older stuff forever, assuming it is even possible.
There are solutions to keep a server online or to give ways to run a local server (a docker image comes to mind), but you cannot think a company will keep a server active after years to just make few dozens happy with all the implications.

No shit, Sherlock. That's why the tenable and preferred option is for them to give it up once they're done profiting so that the public can do it themselves instead.

I agree on the spirit of the initiative, but I cannot really see how it can carried out: my fear is that some types of game will not be sold anymore in EU: no legally sold copies, no legal obligation to keep the server online forever. And in this case we all lose something.

LOL, nothing but FUD. Game publishers made plenty of profit before they came up with this "live service" bullshit, and they'll continue to make plenty of profit even after we stop allowing them to screw over everyone too.

In case you weren't aware of it, the only reason we grant copyright to creative works in the first place is to encourage more works to be created and eventually enrich the Public Domain. If the works never reach it (because the publisher is using technological means to destroy it before copyright expires) then they have broken that social contract and don't deserve to be protected by it in the first place.

These live service game publishers are trying to eat their cake and have it too, and they simply aren't entitled to that. The fact that they've been getting away with this theft from the Public Domain is unjust and must stop.

If you aren't supporting it anymore, then you aren't allowed to maintain exclusive access to it anymore. When you stop supporting it, then you now need to free the code and let other people run their own servers. That does not cost you money.

If you don't want to do that, then you have to keep supporting it. It's that simple. Your right to maintain exclusive access to the source code of the software you are providing to people for money, is contingent upon you keeping the software in an operable state. If you are no longer capable of or no longer want to keep the software in an operable state, then you no longer get to keep the software private. This is not rocket science.

If there are third-party libraries you are not allowed to release by contract, that's fine don't release them. Nobody is saying the source code you release has to be fully functional and have an easy-to-use build system, people will figure out ways to disable those functions or replace them with alternatives. Cleaning up that kind of legal mess before hand or not getting into it in the first place would be kind of you to do, and polite, but I don't expect it from a greedy miserable corporation. Honestly, I wouldn't even be that bothered if they didn't have to release source code at all. What I particularly care about is them losing the right to send copyright-takedowns when people try to share ways to make their own fucking game work. That's the bare minimum acceptable standard required here. If you are not selling the game or supporting the game, then you do not have the right to shut down the people voluntarily doing it for you.