Now this is unexpected. Nikon patented two version of a new 24mm f/1.8 lens: One for a Full Frame mirrorless system camera and one for an APS-C mirrorless system camera. I really don’t think Nikon plans to launch two new systems in 2018. So my guess is that they are simply trying to play with all options. At the end we should expect a FF or APS-C system only.