From page 13 of the review:

"With ZFS out of the picture, Brtfs presumably eliminated due to its licensing, and future development of ReiserFS uncertain, its hard to see where Apple will get the modern file system that it so desperately needs other than by creating one itself."

There is one BSD licensed option I can think of: HammerFS. However, considering the fact that the creator of BFS is an Apple employee, I could totally envision them creating their own from scratch.