MMO's have been seen a good way forward for gaming - sure, the upfront expenses to actually be a mainstream player are somewhat staggering, but the gains once and if you get there are pretty neat, and it's one very efficient way of bypassing the entire problem of piracy.
With the early success of EverQuest and the breakthrough of World of Warcraft, World + Dog decided that now's a good time to develop an MMO and get a cut. 'Now' being 2005-2006, with some major launches last year and this year.
Judging by european and north american traffic though, we'll be seeing a few more of the major releases go titsup sooner or later. I'd judge Age of Conan to be a good candidate for this, due to a very low player count and a (probably) fairly expensive development cycle.
Games with very strong IP ties - Lord of the Rings, Warhammer and - naturally - Warcraft seem to be doing allright, alongside EVE and Second Life. Warhammer's a bit too new to judge yet, but if they manage to keep quality somewhat high, I have a hard time seeing them do a sharp nosedive anytime soon. Various small indie games are also doing well - Tibia is actually right up there competing with Warhammer and LOTRO in some regions.
A number of the big, expensive productions in the SciFi and Fantasy space without very good IP ties will have a hard time recouping development costs and justifying further development, though. And, as such, will look less attractive compared to the few that do sport a larger userbase and to the absolute multitude of Free2Play games that tend to sport content that's limited but hard to beat on price. Many will die.
This is not to say that there isn't room for original ideas in the MMO space - but it seems that in order to sell anything new, you need either well known IP or a way of stealing large chunks of community from World of Warcraft. Thus far, few seem to have found a way of executing the latter. Design elements from some of the more novel, yet successful, games such as EVE Online and Second Life could well be key to this.
It's also quite possible that the next big mainstream title could come as a dark horse out of a Korean software house as a Free2Play game that appeals to western audiences.
