Well, a friend linked me to this forum and i was just reading this and i thought i'd just put in my input.
So… I was thinking... I remember that it was once mentioned that the crew's ship was a very important nakama. So maybe... the 10th member (i believe it's the last since Luffy's original plan was for only 10) is not even one of flesh, but one that has been with them all along. Maybe it's their ship. I mean, ok their first one basically died, but it's still being carried along in the newer body that is the thousand sunny.
And thinking it through, every member of crew has had some Strong and Real reason for being there.
A vice captain/swordsman because every battle has this insanely powerful swordsman and since swords are Luffy's weakness, it makes sense that his vice captain is there to cover that end.
A cook and a fighter since every fight has a non weapon user who is also madly strong. Also, Sanji's less noticeable skill for doing "undercover work".
A shipwright, for obvious reasons.
A marksman, since many strong crews revealed so far has had a very good sniper on board. Also, not forgetting Ussop's talent of deception and his inventiveness.
A navigator and a sort of elementalist, area of effect kind of damage giver. Also Nami's forgettable ability of pickpocketing and treasure keeping.
An archaeologist, because as they get deeper into the story and more about the poneglyps are revealed there will be a need for someone to read them. Robin is also able to keep her cool and maintain a level head in very surprising situations, a good quality for an advisor - something a lot of the good crews have.
A doctor, and someone who can communicate with animals.
A musician, cuz lets face it, most pirate crews of old had a musician to keep the crew entertained during their voyages. And there might be a need for another swordsman since more of them seem to be coming up, and if Brook doesn't get stronger at least he can take care of the weaker lackies.
And then there's the ship to cap it all.
I read a few arguments to how the crew might get a fashion designer since Oda is creative enough to probably think of that. Well, here's my retort, Oda is indeed hella creative, but he's no fool, and if every member of his crew has had such a good purpose for being there, even though on the surface they might've seemed sorta useless or just a burden , then unless there is a seriously good reason for why he needs a fashion designer on board... I mean why not then come up with things like a gardener or maybe a giant?
IMO, the crew is already set and ready, and any new members will just add to the overall strength of the crew.
So yeah.. that's just my views... Nice to see that there's a one piece forum.. actually seeing the community. Gotta thank my mate for the intro.
Peace,
Jacob.