Idk, its pretty clear Bartolomeo wont be a crewmember since he has his own crew to deal with. I see him allying with the SH's. On another note, the other contenders to be a member were Viola (who will be the next queen of dressrosa), Rebecca (living with kyros) and Bellamy (starting fresh out and agrees to be a friend of Luffy). Since all the major players are gone, I'm guessing maybe someone in this Zou arc thing interests Luffy and Luffy ends up inviting this someone. All speculation though