As much as bloggers like to kick and scream about it, the fact of the matter is that theme park MMO's are what the consumer base is buying. They have the best IP's and the biggest budgets for advertising. See: SWTOR.
There is a growing trend lately to make theme park MMO's more solo friendly. Or, in some cases, completely solo-able up until end game. Regardless of what you may think about that decision, I was curious if companies would be willing to take the next step and create a small part of the game accessible without being online. The benefits of doing so would be smaller than soloing or grouping in the game itself, of course, but allowing players to bring a part of the game world with them on a phone or on their laptop when they don't have internet available is a great way to keep people hooked.
Firstly, let's talk about the restrictions of such a system. As I mentioned, the benefits would be lower than if you were in game, perhaps you are only capable of storing half a level of earned exp on your offline character, or a certain amount of reputation earned with a faction. This cap would be necessary to prevent people from playing solely offline and not paying for the game beyond downloading this. Once this cap is reached, the player can keep playing for fun, but in order to gain more exp/rep/gold they would have to connect to the internet to "deposit" the rewards on to their character. There would most likely have to be an anti-hack system in place in order to prevent players from exploiting this as well.
From there, all that remains is making the content. Perhaps you could make a side-scroller dungeon, or stick to the RPG roots of the genre and make it more of a classic RPG. I think it would be fantastic to see a game like WoW suddenly in 8 or 16-bit format, like the original Final Fantasy's, or possibly similar to A Link to the Past. Most of the developers probably grew up playing those games, and I'm sure they would enjoy the opportunity to make a retro side-game. I know I would.
Blizzard has been experimenting with branching the genre into other avenues, like its iPhone apps and its magazine (that they rarely ever send out). Even Dragon Age made a Facebook game that has achieved a certain level of popularity. I think there is a lot of room to cater to their audience in ways that are unique to gamers. Indie games are becoming quite a hit lately, with titles like Braid making its way onto Xbox Live. A company making their own "Indie" game that connects to the online experience would definitely work for this crowd.