I'm taking this quote, ironically from someone in the yahoo comments quoting to defend Apple, that is apparently from Apple:

What to expect at the Genius Bar. Before you come in for your reservation, be sure to back up the data on the device that needs help. When you get to the Apple Store, ask a team member to check you in to the Genius Bar, or check in using the Apple Store app on your iPhone. During your session, your Genius will gather information about your system and answer your questions. If your product requires repair, the Genius will discuss repair options, explain any applicable charges, and prepare your equipment for repair. Most sessions last about 15 minutes, but some may take longer, depending on the issue.

While the data may be your responsibility, and even Apple warns you to back up the data, the "Genius" in charge of fixing his phone obviously didn't follow protocol. I think that's what could make Apple liable, that they didn't uphold their part of the service agreement.

The idea seems to be that multiplayer games allow players to keep playing indefinitely

Not really. Games only have so much content. Multiple people will get bored of that content eventually just like a single person will in another game if the content doesn't have something engaging. In fact, I would argue it's the opposite. Multiplayer games by design have a very short lifespan. Multiplayer games ultimately lack a lot of content because they rely on the players to create an experience for each other and developers don't want players to play indefinitely, they want them to buy the next game the following year and move on. Even if we give developers some faith, people still eventually get bored. DLC exists for both multiplayer and single-player after all. It's not a problem exclusive to one or the other. Single player is endangered not because it isn't engaging, but developers are AFRAID of creating a satisfying experience. If games are satisfying, they have a longer lifespan and companies can't make games as fast and people will get burnt out on the franchise (see Assassin's Creed). With multiplayer games, they have the work of the community. No one plays the old multiplayer games anymore except for in LAN setups, there's not any content left because so much of it is driven by the community that people are FORCED to buy new multiplayer games, while a single player can still go back to the old Elder Scrolls, Fallout, or Witcher games and get as good of quality experience as they did the first time they played.