Goodness. The real measure of the success of Second Life is concurrency, not new registrations. Concurrency is the number of simultaneous logins and that has been growing reasonably steadily.

As for the claim that there are too many bugs, that is obviously the case, but in fact, the LIndens are doing a miraculous job there: WoW doesn't support LInux. Neither does EQ. And there's no feedback mechanism in place where complaints can be heard directly by WoW developers. Linden Lab hosts in-world meetings weekly with a larger portion of its programming staff to hear complaints and suggestions.

Also, few of the other virtual worlds out there are open source, and none inspire developers to develop compatible alternatives implemented in different languages.

FInally, none of the other virtual worlds have assigned themselves the lofty goal of becoming an internet standard. There are high-ranking engineers at Linden Lab whose job is to ensure that interactions between the LInden Lab hosted "Second Life" become 100% compatible with the worlds hosted by rival organizations so that teleport between worlds (and eventually walking between them) becomes commonplace.

To suggest that Second LIfe will die is to ignore that it is growing in ways that no other world is even trying to.