There is no such thing as an "H3" body.
If you want a platform for a non-hasselblad back you can buy an H2.
Despite rumours to the contrary the H2 is alive and well, the H2D will be discontinued
I know, and that is my point. In a sense there is an H3 body (the backs and VFs are removable) but that body is only to be sold as part of one of several H3D system kits, the H3D-22 or H3D-39.
I can imagine that H3 body, Hv6, and such all being sold only in kits that also include a D back, while the H2, 6008AF and such are the only options still sold "body only". Given the existence of the 6008AF as a vehicle for customers who use film only or are not yet upgrading to a new digital back, I am not as sure as some are that the new Hv6 body will be available separately.
Instead I suspect that soon enough, most or all new D backs will be designed to use extensive, proprietary communications with the body, VF and lenses, and thus require new bodies supporting those same communications, ruling out "max and match" between brands, or between new backs and older bodies.
Nothing I have read so far about the Hv6 suggests instead that it will be available "body only".