A dpreview forum member contacted Zeiss and asked them about any potential ZK lenses being developed in the future – the answer was that Zeiss has no plans to bring back the Pentax ZK mount despite the recent introduction of the K-1. Here is the full email:
Thanks for your inquiry and your interest in our products.
Unfortunately, we had to discontinue our ZK type lenses in 2011 because the request was too low.
We do not plan to offer K-mount lenses again within the next future. If Pentax reaches a similar market share among the full frame bodies like Canon and Nikon, we will reconsider it.
For further details, please do not hesitate to contact us!
With best regards,
Kundensupport / Customer Support
Camera Lens Division
Carl Zeiss AG
73447 Oberkochen, Germany
Few Zeiss ZK lenses are available for sale on eBay.