The introductory price of digital cameras has dropped a little, or at least stayed the same over the past several years. Only when a new series is introduced, has the price gone up. If you consider inflation, prices in yr 2000 dollars have dropped a lot.
I'd expect a 5D MK III to be $2800 just like the MK II was. Nikon reverted to the original D700 price for the D800, and Canon won't cbe much different.
If there is a new higher spec model, then we will see a higher price, but the D800 has pretty well established a price bar considering the features it has.
A 4K video DSLR will be a much more expensive unit. Just go out and buy a 4K monitor to see the image with, if you can find one. They are coming down in price, no longer 70K, they are half that now.