The odds of him adding Pigmen are still very unlikely. I want them also, but don't get your hopes up.
I have faith that mojang will do what is in the best enjoyment of players. Remember how everyone was against the whole trading villagers thing, it turned out to be a very useful addition. I have alot of respect in dinnerbone, the creater of this new mob, he has added alot of interesting items so far, each of which I enjoy all the time when using the latest snapshot. I'll enjoy the wither, wither skeleton, npc zombies, and this new mob. Whether it be pigmen, panda, or some fat tubby frog that goes around eating every block, I'm sure to enjoy it.
I made a topic suggesting Ghast Jockeys, sounds similar to what you're describing. Back on topic, I'm clueless as to what this mob will be, if not Pigmen. Has anyone even heard much from Dinnerbone recently on this mob?