Even with all of pitfalls listed above, there is still room for MMO games to find their own niche in spite of the WoW juggernaut. EVE Online is a great example of a title that has managed to expand its user base during the World of Warcraft era, and that is because of how distinct the game's universe is from WoW, or most other games for that matter.
It is for that reason that we think that Champions Online, Star Wars: The Old Republic, and Star Trek Online all have a good chance to find a unique audience; each title has a distinct feel compared to World of Warcraft and each already has a well established continuum to draw upon. Final Fantasy XIV should benefit greatly from the Final Fantasy brand name along with tapping into the fertile MMO ground of consoles. NCsoft's Aion, however, will have a harder row to hoe because of its newly created universe, its high system requirements and because Korean made subscription games have had some difficulties in finding audiences in the West.
We wish all newcomers the best of luck, but we don't think there's likely to be a true competitor for World of Warcraft's massive subscriber base anytime soon. In all likelihood, the next MMO to shoot up into the millions of subscribers will be the next mysterious MMO from Blizzard themselves.