This seems to be a popular time for noting network effects and the death of social networks. Two graduate students got remarkable coverage of applying epidemiological models to MySpace and Facebook, finding that Facebook’s pattern in Google searches is right about where MySpace’s was as it entered its decline. For our in-game social networks, Tobold is predicting the death of MMOs as a genre. (By the time this post goes live, there may be a post from SynCaine explaining that EVE is doing it right and will still have a growing playerbase even after we have our own spaceships.)
Just as economists predicted nine out of the last five recessions, the impending demises of Facebook and World of Warcraft have been predicted every three to six months since the 1980s (I may be exaggerating). Whoever happens to have predicted those most recently when they happen will claim credit as a great prognosticator, and whoever has ever predicted them can claim to be right in principle, just off on the timing.
Given precedent, when one of these systems collapses, “collapse” is usually a better term than “decline.” The same social effects that drive adoption drive abandonment. Again, timing that collapse is really hard even if it is obviously impending; “the market can stay irrational longer than you can stay solvent),” and just because you recognize a bubble does not make it pop.