Phase One, Mamiya, and Leaf are all one company now. Phase One at the announcement of the XF stated that support for the credo backs was coming sometime in the future, in June of 2106, that make 1 year.
You ask a good question on the Mamiya Name, as B&H still lists most of the current Phase One/Schneider LS lenses under the Mamiya name. B&H does not sell "Phase One backs or branded products" but they also list the Mamiya Credo digital backs, so not sure where this will go in the future as all Phase One dealers can sell Phase One or Credo backs. But it does seem that a lot of the same lenses are still sold under the Mamiya brand.
All of the Phase One LS glass that is purchased with a "new" back get a 5 year warranty, currently this does not hold for back upgrades, which seems a bit strange to me. All of the Mamiya LS Schneider glass on B&H show 1 year warranty.
The LS lenses, although Phase makes a point of stating German design from Schneider, are still made in Japan, as is the XF.
Lots of cross over, it's safe to assume Phase One parent company can currently draw on a lot of different resources to produce products, which is good.
Hopefully for the Credo users, the XF support will come soon.
Paul C