My problem with things like this is that they mandate labor from others without compensating them.
The obvious and clearest response is simply this: If you as a publisher are so convinced that your game is obsolete... make the remote server source available under a permissive license to your existing license holders. Better yet - plan for releasing a copy of it at development time.
You don't even need to make the license permissive to everyone, or for everything (open source). You just need to make it possible for those who have purchased your product to continue to use the product, and there are MANY ways to do that which don't involve your consistent labor.
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Basically - To directly address your point: If the alternative is that the publisher does crap like completely disable single player experiences because they've shut down remote licensing servers... fuck them.
That's not a company I think should be allowed to exist. If we can't limit them this way... them I'd be fully in favor of mandating they return the full purchase price of the item to every purchaser.
That purchase price represent your customer's labor.