I'm not really sure MMOs are the future to be honest. The model of streaming content via the internet though probably is. There are services out there now that allow you to play any game from basically any computer. It eliminates the need for system requirements bottleneck and you just stream your vid feed and commands to the game. That's the future of PC gaming in my opinion. The only problem there is the crappy bandwidth across the US.
However MMOs have their place.
In college I was able to play video games with my roommates and my friends and we had great fun. Then we moved all over the US never to see each other much. But WoW has fixed that. I currently play with college friends and high school friends that are now in different states and different countries. If left to my own devices I probably would forget to email them, forget to stay in contact, and move on. But I'm able to bond the way we always bonded, through video games. It's great to keep that connection and it's the main reason why I play.
I love my single player games and I still can't stand playing Madden with anyone else because I'm too competitive, so I'll always keep up my single player games. But MMOs definitely have their place for me.