Bah. WoW will fall when it's time. Its starting to get in its mid-age I believe since it has released a lot of expansions, content unused, and graphics that are beginning to be old. Other MMO's are starting to show progress, but WoW is simply too well known and large enough to stand tall for a little more time, plus a community that is completely addicted to it that it will still be populated for years and years even if there may be better ones out there.
What the other MMO's need is good advertisement, a great development team that listens to the public, balancing and updates, great release, and a fantasy that will suck people in, with great graphics to help the eye. The other MMO's around have failed in a couple of these things but I consider them trial and error until a company that's been seeing how they failed and such comes up with something that will gain at least a close amount of the popularity that WoW had.
When that MMO comes out many will hate it just like they did WoW and we begin everything again saying its the best thing ever and no other MMO will topple it... again.
Anyway if you want to leave it so be it, just remember don't think you will always be in WoW forever saying everything else sucks. Start looking at other things and keep an open mind and an eye on the development of other MMO's.