Over the past few months there has been a lot of buzz about Rift. Lately that buzz has started to swing back around to a predictable backlash. Green Armadillo and Ardulf have great posts about it up, and I think there are some legitimate concerns. However, I also think that predictions of a WAR and AoC style disasters are likely overblown.
You can be almost certain that Rift is going to lose at least half their players by the end of the first month. WoW but with better graphics, more flexible class designs, and Public Quests doesn't sound to me like it's going to be very sticky with "WoW tourists" (a meme I hate, but I think it may apply here). Even if Rift is a better game, for many players I think WoW has too much social inertia for a game competing in the same genre to overcome in the long haul.
That said, I don't think launch Rift is going to be broken like WAR and AoC were. Many commentators seems to assume that the crash and burn the latter games did was some inevitable consequence of trying to compete too directly with WoW. However, I would say those population implosions were a consequence of horrifically bad launches, not some sort of law of the genre. As long as Rift doesn't launch with an absolutely stupid number of servers, crippling their long term population and thus the PQ style Rift system, I think it's going to be a much better game than either AoC or WAR was at launch. Rift will surely lose a lot subs in the first month, but I doubt we are going to see it collapse into a singularity. I'm thinking more like a steady 200K-300K subs by the spring (i.e., EVE or LoTRO rather than Vanguard or WAR).
Despite my conviction that Rift is going to be at least "pretty good" when it launches and do "at least OK" on subs, I have no intention of being there for launch. I'm simply glutted on fantasy MMOs. If I want to play a fantasy MMO, I already have characters in WoW, LoTRO, DDO, Wizard 101, and EQ2X up and running. Between them that is an amazing diversity of tones and play styles. Short of those, I'd be more inclined to fire up Dark Age of Camelot, Allods Online (it really is fun for about the first 20 levels), or AoC (it's a lot better now than at launch). There's even Guild Wars and Vanguard, neither of which I've ever played and I can try for free instead of paying $50 for a box. Regardless of how pretty or spiffy the "next big fantasy MMO" may be, I just don't need another one right now.