One reason why I think the WT will continue is that most of the projections of WT doom are based on their current policies and activities.
WT has changed a great deal over the past 5 years: down sizing, cutting printing and convention releases, requesting money, selling properties, boosting their legal team, going online. They are reacting to various pressures and will continue to do so.
They are definitely past their prime and under pressure, but without a major change such as losing charity status or the GB in prison, they have years left in them yet.