Open Ended Gaming
One thing that Ultima Online got right was allowing players to build houses, castles and other structures to use as a base from which to operate. Blizzard would be wise to let their players do likewise. The sheer numbers of players would make large guild wars very interesting. Commando raids on fortresses to retrieve items or even large scale siege of a castle would be epic.
Middle Earth Online (now titled Lord of the Rings Online: Shadows of Angmar) is waiting in the wings and no doubt the developers have studied WoW very closely especially user complaints. MMORPG's are, in my view, in their nascent stage. Now that broadband is widely available, and consoles becoming ever more powerful, it's likely that a WoW type game will soon launch on PS3 or Xbox360 with great success. The benefit would be the stability that platforms allow and less configuration problems for users.
Currently Americans spend more on computer gaming than on movies. That's a trend that's only going to increase. Today's kids always had video games. Old people like me remember when 2600 launched and we reveled in 4 bit glory.
Me: "See that yellow block, that's you. I'm the blue block. My block is going to try and shoot your block and you have to shoot me."
Brother: "This doesn't look anything like the box."
Me: "Shut up and play"
It was a new thing. An entirely different type of entertainment. For kids who are teens now, there have always been video games. They're just another type of entertainment. Interactivity makes them prize gaming above the passiveness of movies. Movies will always be there, but they'll also always be second to gaming.