The real problem with the Z series is that there are60 years worth of F mount lenses around most of which will work on a Nikon DSLR. The Z series has been around for less than 3 years, understandably there are fewer lenses available and a smaller range. Persuading people to discard the old system was always going to be difficult, particularly when the old is still in production. When Nikon went digital the first DSLR was the top of the range D1 followed by the D100 coming in with a middle of the range camera seemed strange to me at the time and remains so. I would have expected that the F6 replacement would have been the first Z series camera simply because some professionals do actually wear out their cameras and lenses meaning that they have to replace them. The middle market buyers don't, on either count, so it is a case of persuasion rather than necessity. I have no need to buy a new camera so why would I want to buy a Z6 or Z7? Once you have a decent number of professionals using the system, and breaking lenses, you have a feed to the used market, the more so if you upgrade the lenses along the way. The number of used Z6 bodies available suggests that people are upgrading from them already, whether they are moving up to the Z6 II, Z7, Z7 II or back to SLRs isn't easily determined.