i would absolutely LOVE for that to happen, but...no, i don't see that happening...
How about this for a new crew member: A Chick who was originally a guy (obviously from a Devil Fruit, but can't switch back).
I can imagine the look on Sanji's face if he hears about this one. Heeheehee. ^_^
perona/ace/hancock most definitely
If hancock joins the crew it going to be bad news for chopper. "who put this deer in my path!" not to mention her big snake trying to eat him.
i think that Hashi the fishman theory is the best
1. usopp had a scene were he would almost drown in the aquarium trying to get some fish.
2. Hashin has been in the story before.
3. He has shown great nakama aptitudes.
4. He cooks
thats about enough for luffy....
Don't know if this has been said what about BonBon, Aka Okama, Aka Mr 2.. Coz he/she is in Impel Down. Luffy could save him/her. Would be funny to have an Okama in their group.