I think it's safe to say Nikon is watching costs and trying to maximize profit. The declining yen make it easier to export from Japan, but many of their products are made in countries where currencies are linked to the dollar or yuan.
There is a limit on how many cameras a company can market at on time. The D800and D600 have pretty well tapped them out. You also have the Nikon 1 and D5200 releases.
My guess is they are riding current new products and will release a very much improved DX camera later this year. DX has an important place but needs to be positioned the right way with lenses and avoiding competing with other Nikons.