There are a few organizations in the Aikido world but thre is only one Aikido. Aikido principles will forever remain the same but the variations, however, always has room to mutate. O-sensei said that he never did the same technique twice in the sense that a human cannot duplicate the exact angle, stance, etc as the previous technique if you were to repeat it. He also said that depending on the situation, you may have to create new techniques to fit the ordeal you are in.
So, if O-sensei were still alive, I believe his fundamental principles would remain the same but his ideaology would could continue to grow.