I agree with Sanshiro's definition of dying, yes. And with Charlequin's expanded definition: "If things continue as they are, then this franchise will die." Since it has been continuing on this path for over a decade, we have a stable and consistent pattern to follow.
Most franchises die, some just do it more slowly than others. I have a more interesting question: which franchises are not dying? That is, which have seen significant growth or stasbility in the last 5 years?
Please note that new franchises can't count, here. Monster Hunter, for example, is still in its growth phase. What I'm looking for is a franchise that has clearly reached an equilibrium, or a peak, or whatever you'd like to call it, and then maintained consistently strong sales for years or decades.
Dragon Quest is an example of this, while FF is not. Pokemon is quite stable. What other franchises maintain consistently strong sales?