I just looked up C&C4, and I think I just died a little inside. This seems like it will also carry over to Steam. Having to stay online for a single-player game is the worst idea ever, but people will see the name Command and Conquer, buy it en masse, and won't realize the DRM scheme until it's too late. Hell, maybe they won't notice at all! They're all hooked up to their giant desktop computers, getting Internet 24/7, and they won't notice the shackles that are being tightened around them!
At the same time, I do not see this failing. They released The Sims 3 so that owning a pirated copy is the same as owning a demo, and were ultimately pleased by that fact. When EA sees the number of pirated copies of C&C4 that are unable to work because they can't constantly be authenticated by a server, they'll applaud themselves for being so brilliant. Other companies will take notice, and use the same tactics. "If you want to play the game offline, you're obviously up to no good," they'll say to the gamers calling their customer support, who have anger in their voices and overwhelming disappointment in their hearts.
And as the years go by, some corporate executive will see the servers still being used for authenticating Command and Conquer 4, and they'll say to themselves, "No gamer wants to play this any more! It's old!" The server will be shut down, and the man who was once a boy, enjoying the latest fight against the Brotherhood of Nod, will be filled with sadness, for they can no longer enjoy the product they once purchased, because some money-grubbing corporate executive decided it wasn't worth his resources to give their customers their money's worth.
It will all become rentals. You can only play the games you buy on their terms, but don't even think about asking for a lower price. Games aren't considered serious art by the majority, so they won't lift a finger to regulate this madness.
And don't even think console-owners are safe, because it's slowly spreading that way, too...