That's not dying in the sense that being in maintenance mode is not dying. A game in that state is squeezing the last stream of revenue out of the residue of the player population who can't make themselves quit. This can be a prolonged process, but the game otherwise has no future.
The real turning point in an MMO is when revenue drops enough that an adequate stream of new content cannot be maintained. Is WoW at that point? It depends on how successful and sustainable their monetization strategies are.