The brief appearance of a GPZ900R in TG2 will boost demand for them a bit but they’ve been fetching decent money for a while now so I think the biggest difference will be how quickly they go rather than how much they go for.
I annoyed my wife a while ago by showing her adverts for GPZ750 Turbos because she sold hers about 10 years ago for half their current asking prices but I might be able to talk her into getting rid of her 916 before it needs the belts changing without being ridden again