I still don't think it's John's.
I think they're trying to get as many of the minor yet memorable characters on screen in case another mini doesn't happen. Try and tie as many loose ends as they can.
Instead of seeing Zhaan again, I keep on thinking the 'big shocker' is Moya blowing up. Or Crichton going into a coma. Or Scorpy sacrificing himself for John's safety. Or even Aeryn dying after childbirth.
