I own a blad, but there is no way I can afford this back (yet). Nor would it be justified for the shooting I do. That said, if Nikon would offer backs that would fit their older cameras I would be in the market, especially if they were <$1000 and FX sensor size, even if "only" 6 to 10 MP.
I want a digital back for my F3HP and my 90s please.
The only way this will happen is if Canon does it first. Let's be realistic, there is no reason for Nikon to shit all over it's most profitable, sub $1k market with a support-intensive, low margin piece of gear.