I was sure there would be a huge market for these backs, if they were sensibly priced between 5000-6000 €. But I suppose Hasselblad have done their homework already, and found out that it isn't worth continuing this platform. The first back with a square sensor was a great idea, the idea to put a rectangular sensor in the same back wasn't.
Anyway, in my area, the V-mount still seem to be the most represented backs. If there are 12 backs I know of (all professional, nearly all allrounders, shooting all kind of photography), 2 are Hasselblad, 1 Leaf. 9 are Phase One backs, and still 5 of these are V-Mount backs used on 500/RZ/view cameras. (the rest Phamiya and Contax). The day, Phase One will have a Hy6-type body, fully modular, with optional WLF, most will switch to the M mount (me too)
Tom