There's nine members already. Oda's already confirmed that the ship is counted as part of the crew. Back when he announced that he was gonna kill a crew member during the Anus Lobby arc, he killed Going Merry. So, we have:
Zoro, Nami, Ussop, Sanji, Chopper, Robin, Franky, Brooke, Thousand Sunny, ????
Maybe Hacchi will be the last one? Who knows, he has attachment to his takoyaki stand and Camie and all. I have a feeling they'll drop Camie, Hacchi, and starfish thing at Fishman island, pick up a new crewmember there, and then it will be GO TIME.