It's been done before
, Dicomed Bigshot, 60x60mmhttp://www.epi-centre.com/reports/9604cs.html
$55K for the color version back then.
Maybe 56x56 chips can be done quite easily today with 9um pixels, using existing tech? Would be a nice 39 megapixel fat pixel back! Problem is that it would be a huge risk for Hasselblad to test this market, and I don't think they are in the position to take such a risk...
How many would pay ~$50K for a full-frame CFV back?
I'd be all over it