Via Neuroskeptic, I just found out that the Big Five have been proposed to appear (sorta) in the DSM-5.
The current Axis II disorders will be replaced by a mixture of continuously-rated personality disorder types (carrying forward psychopathy, avoidant, borderline, obsessive-compulsive, and schizotypal) and 6 personality traits. According to the rationale, four of the traits are pathological versions of 4 of the Big Five (Openness/Intellect apparently doesn’t have a pathological extreme).
I need to read more about it, but it’s not clear to me how redundant the types and traits will be, and whether that’s by design. For example, the typology includes a schizitypal type, and the trait space includes a schizotypy dimension (the latter based on David Watson’s work suggesting that trait terms referring to oddness/eccentricity should not have been excluded from the lexical sampling that produced the Big Five). Both are continuously rated — will they provide complementary information, or will they just say the same thing?
One good thing, though, is the shift toward using continuous ratings rather than yes/no categories. This will potentially create practical problem for the healthcare system (if something is continuous, at what point do you decide that insurance will reimburse treatment?), but scientifically it is better in line with what we know about the underlying nature of personality and personality disorders.
The Hardest Science 
Having both 5 “PD types” and 6 “personality traits” is something that only a committee could have come up with. Someone will have wanted 5, someone else 6, and this was the compromise.
That said, I think moving to a dimensional system is in general A Good Thing.
I don’t have any inside knowledge of the politics or process, but that sounds pretty plausible to me. I know that a number of personality psychologists have been pushing for some years to extend the FFM into a model of psychopathology (and doing the basic research to make that happen). And I can imagine that there are plenty of researchers and practitioners who are heavily invested in the old Axis II system. So the traits probably came from the former camp, and the types from the latter.