OK, that clarifies things a bit; thanks. The remaining questions probably are ones that can only be answered by F&H, Jenoptik and Phase:
(1) Will there be a "generic" Rollei Hy6, to which backs other than Sinar or Leaf can be attached, or are all Hy6 cameras going to be allocated to Leaf and Sinar and sold under their respective brands only? If the latter, then, as Yair noted, the Hy6 platform will efectively (even if not theoretically) be limited to Leaf and Sinar, because neither company plans on selling its Hy6 cameras separately from its own backs. So, even if Phase decided to make its backs available in Hy6 mount, they wouldn't have any cameras to put them on, unless there's a generic Rollei Hy6, OR unless it cuts the same sort of deal as Leaf and Sinar and gets Jenoptik to make Phase-branded Hy6s, which Phase would bundle and sell with its backs.
(2) Does Phase plan on making its backs in Hy6 mount anyway? If not, then all the theorizing about the Hy6 being open to companies beyond Leaf and Sinar is irrelevant, because it seems unlikely that Hassy's going to be interested in the Hy6, and therefore the only remaining back maker left out of the Hy6 bandwagon woud be Phase. (Of course, since there are a LOT of people using Phase backs, it's a pretty big deal whether Phase participates or not)
One other comment: I realize it's not entirely rational, but I really don't like the idea of owning a Leaf, Sinar, or Phase camera. By that, I mean a camera called the Leaf, Phase or Sinar Hy6. Rollei makes cameras. These other companies do not. Thus, the name of the camera should be Rollei. (Yes, I realize there are strong marketing reasons for the back makers to want to "brand" the whole package. I just don't like it for aesthetic reasons.) It'd be like my MacBook Pro being called the IntelBook Pro since it has an Intel chip. Apple makes computers, Intel makes processors.)
The Hy6 and the AFi will come off the same manufacturing line and as far as I know are going to be 100% similiar to each other, except for the badge.