Well obviously if the Bryans were injured, someone else would HAVE to play... but actually I bet PMac would go with, either the uninjured Bryan and a singles player (Andy or Mardy), or he might go with a team like James and Mardy who have played doubles together, won some titles, and have played DC doubles together even.
Basically it took the Bryans winning a slam and getting to the top of the rankings before PMac was willing to take a chance on a pure doubles team and now the Bryans are as close to a guaranteed point as we have. So I think that if they couldn't play, he wouldn't want to take that risk so he'd have at least one play-able singles player in there.
Just my opinion
Sorry Andrew lol