I think the grandmaster pet for life should be centaur, satyr, or natures wrath(the tree person thing).
I agree with AlicornsPrayer, and J3R3MY having the natures wrath wouldn't make sense, there is already a natures wrath pet you can get from a boss. You already get satyr when your level 48 and centaur would be sorta weird if it was in small version i would think. Having more mounts, what a pain. If there would to be ever mounts and pets given at a certain level then it would be most likely they would raise the level cap.