If Nikon marketers understand buyer's psychology they will want that FX entry camera. (And "entry" does not mean cheap and poor quality by any means).
When I decided I wanted to step up to a better camera from my D5100 (which when I bought it was the camera one step up from the 'entry' level D3100). I looked at the D7100, almost bought one. But it was a case of "for a few dollars more you get to go FX". This is the lure of the D610. It tempts you for just a little more (relatively speaking) you get to move up to the next class of photography.
Much has been written about whether FX images are better than DX images. I shoot both. People at Nikonites with DX camera take fantastic images. But that's not the point. FX is a different class. Most professional lenses are FX. And they cost more - presumably Nikon makes more money (per unit) off of FX products. (I suspect overall they sell way more DX cameras but that is another story).
Anyway, if Nikon wants to lure people into the FX world and sell us lenses at $1,000, $2,000 and more per lens, first they have to get us into the FX system. .... so they need a camera that the sale clerk can say "well for a few hundred more you can go FX" and say it in a way that makes you feel special. It is not the gap between the D610 and D750 that matters (and when I was shopping it was the D810) it is the gap between the D7200 and D610.
Worked on me.
And I don't regret it.
Not even when parting with $1,000's for lenses.