Europeans can save videogames from being destroyed! The European Citizens' Initiative has just launched and represents the biggest and most ambitious chance...
It's available as an official European Citizens' Initiative Proposal.
Short version: it's a campaign to force publishers to provide some way to play online only games after they decide to shut down the servers. That or letting us know, by law, that games can be killed without repercussion. It's not about forcing publishers to keep the servers alive forever if that's what you're wondering.
Long version: check out the official website for the Stop Killing Games campaign. It has FAQ with all the important info.
Unfortunately not, initiatives can only be signed by EU citizens. For this specific campaign you can help by spreading the word, besides that you can also check the "Take Action" tab on the site I linked previously - there are multiple campaigns started in various countries so you might be able to help with one of those.
Would this include the availability of playing single player offline games without the need to log in to different accounts and signing in to third party clients?
That shit makes me completely crazy. I just want to build a pretty little city all by myself, why in the world would I need to be online and sign into shit for that.
Not really. This isn't about completely preventing publishers from adding account systems etc. (even if that would be ideal), it's about publishers removing your ability to play games after they the shut down the servers. The former would hopefully be a side effect of a potential law change/ruling but the main point is keeping games playable after the official support ends.
In your example it could be removal of the sign in requirement once the account system is down but not necessarily preventing them from existing in the first place.