This would work, and would likely not be too hard (assuming nothing is encrypted). But two problems with that approach spring to mind:
1) Firmware updates could easily break Phase's reverse-engineered compatibility.
2) At least in the U.S., a not-so-popular little law known as DMCA (Digital Millenium Copyright Act) might be able to prevent such backs from being sold here.
Still, I'd be interested in evaluating a solution regardless--Like everyone else, I just need to see the details to be able to make a good decision for my photography business.
P.S. Or, it could be they're having trouble finding a Hy6 to buy... (kidding)
If Phase wants to do it, they only need to buy a camera body and figure out the electronic contacts.