I've got to agree, I hope they don't go nuts with expansion packs. Look at a game like Everquest, which used to be the King of MMOs, but severely lost its quality after the first 4 or 5 expansion packs and then became a joke after the 10th! http://bit.ly/f7zVsd

Thing is I think Blizzard know this. There is still one unnamed project in Blizzard development alongside Diablo and SC2, and ill bet anything its a new shiny MMO. Whether its Warcraft or not remains to be seen, but i really wouldnt be surprised if by the we get to WoW Patch 3.5 or whatever that there was a new Blizzard MMO on the horizon.
http://bit.ly/foMYQL

I'm guessing WoW will be like Halo 2 or Starcraft. People still play those games, because they were well made and inexpensive to play, even though there are newer games out there.
http://bit.ly/eeZHSn

After that, we start heading back to Outlands to enter the Twisting Nether, probably heading back to Argus (the home of everyone's favorite squid-faces) to take on the true leaders of the Burning Legion, this time not to force them back, but to end the destruction of countless worlds and other species. This part of the trip will likely be where we actually get to meet up with the Titans and take part in a semi-"final chapter" part of the story.
http://bit.ly/ewpz00