It is a matter of supply and demand.
There will still be a demand for entry level dSLR, and that would be DX/APS-C type, with the smaller sensor, smaller shutter, smaller mirror and smaller pentamirror. So, in terms of weight, size and price, lower than the FF type.
I have just got a D3100. That cam has got the right kind of features for my use. This is especially so with the 14Mp sensor. It is simply ridiculous to have 24Mp for a DX camera.
As I see it, there would be at least one entry level DX, one advanced DX like the D300, one hobbyist FX like the D600 and one top of the line pro camera. I believe this is the minimum line-up, but there could be more than 4 at any one time.