User blog comment:Dandalore/Fishman Island!!/@comment-3119203-20111208010540

Shirahoshi will not join. Jinbe may join, depending on what happens further in this arc.

Oh yes she will. At the very least, Luffy attracted her attention, which may turn out to be good or bad.

Of course he is. I doubt Oda would introduce him just to have him disappear eternally. Maybe Oda forgot.