Lord Zack
Explorer
Zuggtmoy will be appearing in my Greyhawk campaign if I ever get enough players and appearances by other demon lords, particularly Lloth, but maybe others as well, may also be in the cards. As for my present campaign Baphomet and Yeenoghu have already had some influence, for one my players just defeated a Baphomet worshiping goblin tribe and will soon be facing the minotaur that ruled the tribe. Also a barbarian tribe that is one PC's enemies worships Yeenoghu. But as for whether they'll have a larger influence or even appearances later on I'm not sure.