So, by the sound of it, we'll be playing people who transform into dragons/have dragon powers? If so, definitely count me interested.
Potentially this can take an "NRP" angle - players are captains unless they specifically desire to be on another player's crew, and until meeting each other are in charge of their own ships/towns/areas of influence.
Well the way these things go usually is we have at least 1 pirate crew and sometimes some marine fellows running around as well. Finding One piece and the benefit of crews is generally a good reason to get into a group of some sort. One of the problems I foresee is a lot of weight is put onto the GM to put a plot out for each island people go to. Perhaps if we had everybody 'make' an island adventure and co-gm/gm it when a group gets there to help spread the weight around so to speak.