Not much real,verified information, but some interesting speculation/extrapolation from the Nikon videos, such as the possibility that the lens mount diameter is very large;so large that,some say, that a digital "medium format" sized sensor might be a possibility for future cameras using this mount. Also, a couple of very fast lenses have been patented, such as a 50mm-ish f/0.95 and a 36mm f/1.2 if I recall correctly. The medium format digital ought to be called mezzo-format, since it's not as large as medium format film, but is larger than FX format. Since Pentax,Fuji, and Hasselblad already have mezzo-format digitals on the market, it might make sense for Nikon to keep that option open as a future possibility.
The new lens mount for this Nikon mirrorless...I dunno...let's see how well the adapter works on F-mount lenses, and what models of lenses it supports or does not support. I can see the desire to launch an all-new lens mount, but I think it's lamentable that the F-mount will not work unmodified and as "native" on their next generation of mirrorless cameras.
This ought to be interesting, to see how much Nikon learned from its dabbling in mirrorless with the 1-inch sensor Nikon 1 model line a few years back. Will Nikon's upcoming FX mirrorless offering(s) be well-executed, or an accidental bullet to the corporate foot? I want to say the former, but the latter outcome would not be all that surprising.