I may be totally out to lunch but I'll say it again - if I were planning a product line based on a similar numerical scheme like Nikons current setup I would be reserving the DZ00 for FX bodies from now on. All the last DX bodies have had the convention DZ000 that's D3200, D5200 D7000.
If anything we should be expecting a D7100 or, if they skip a revision number to line up with the lower end models, a D7200.
It's easy to see how the arrangement was arrived at when the D100 and D1 were launched, there was no way to foresee the phenomenal success of DSLRs and the eventual three tiers Nikon now have. But now it makes no sense to have DX and FX numerically encroaching from top to bottom and vice versa ie: D400 DX and D500... FX or.. DX.. it's a recipe for an advertiser's nightmare with complete confusion in the market place - I just don't see it playing out like that.
Does that have any implication on the makeup of the next high end DX body?? ie: would a D7200 be the upgrade to the D300s? Or would it require continuing a fourth model say a D8000? Hard to say but four DX bodies is an awful lot.
How exactly would a D400 differ from a D7200? and if it differs enough does that make the D400 actually a D8000?