I agree that Neopets has slowly been dying off. I also very much agree with @(you need an account to see links) and their post; at this point Neo is just trying to milk all they can out of their remaining players.
I just feel bad for the small population of legit players with epic-amazing accounts. One day their 330+ avatars, 12304823 trophies, 9999 lvl BD pet and everything else will mean absolutely nothing and probably cease to exist. And they actually worked for it all.
Viacom is still probably making a great deal of $$$ off of it, if I'm not mistaken. And as long as the money flow is consistent, it'll be sticking around.
I think that they'd certainly get more activity if they made the game a tad bit less childish, loosened the filter and generally made it a freer place. That was when it was in it's prime, no? I don't see that happening though, simply because it's strongly affiliated with Nick.
I'd give it another 5 years. To be honest I don't see where the majority of online enterprises are going, it's all a toss up. I mean, just look at MySpace.
I wouldn't be too quick to write off Neopets, just yet. It's bounced back on more than one occasion in the past, and could well do so again. I, personally, would like to see a new plot opened to generate a bit of interest. It would be a good start.