I was surprised to see someone who's been a member here since 2011 asking this question, as I'm pretty sure this subject has come up a few times. The short answer is simply: yes, they can survive. It purely depends on the quality of the game itself. Case in point: the first two Arkham games, the Elder Scrolls series. Hell, Fallout and Dishonored, for that matter. But in terms of "why are multiplayer modes tacked on when not needed/asked for"? You kinda answered your own question. Part of it, at least. Sure, it does indeed give the companies an excuse to make more money with map packs and such, but then again there's some companies that give out multiplayer DLC for free. In a lot of cases, just because YOU weren't asking multiplayer to be added to (x) series doesn't mean that no one was asking for it.
I do agree, though, that I've got my doubts about Batman multiplayer...Batman is obscenely overpowered because he's supposed to be. When you're playing through the campaign, you're supposed to feel like you're frickin' Batman, Batmaning the fuck out of those poor thugs no matter what tricks they try to pull. They'll have to SERIOUSLY nerf him to allow the thugs to even have a chance. But in all honesty, I wouldn't be surprised if there were a handful of people that were asking for multiplayer in Arkham and so they decided to give it a shot. Who knows? Maybe it'll work and it'll end up being the next surprise multiplayer hit the way Assassin's Creed Brotherhood's multiplayer was surprisingly intense, fun, and entertaining.
