I am loosely following the features of the K3-iii because if the past is any indication, Pentax apparently has the tendency to copy features/systems from one camera to another new models. I believe the K3 was the fore-runner for the 645z features. I thought the KP would be a tell-tale of what to expect next, but perhaps the K3-iii is a better indication. Some new features are really interesting, except I hope they stick to the flip screen on the 645z new model ( I use that a lot).
There is also a youtube video on the next Pentax versions. I have no idea how authentic the information is, or whether it is pure speculation. Here is a link to the video:
Do I need an upgraded 645z? Not really. I can do what I'm doing comforably with the 645z.
Do I want an upgraded 645z? Ohhh yeah!!! In this case my "wants" far exceed my "needs".