You are one optimistic fella. But your word in 's ear. Personally I'd be fine with a number of the Dressrosa arc guys being added. Fujitora, DC, Sabo, Burgess, Doffy, and maybe some of his crew and/or more colosseum fighters. Anything else would be a pleasant and welcome surprise to me.
That's really just the upper limits of what I could see them considering. However, I do have a few reasons for thinking we will have at least 15 characters to choose from, and maybe even up to 70.
1. The last game came out 2 years ago. Who knows how long they've been working on this.
2. Koei likes large rosters.
3. If they make some support characters playable, they already have like 40-60% of their movesets ready, thus making like 10 characters equal to more like 5.5 characters of development time.
4. Since most arcs already have stages, they don't have to build as much from scratch.
5. There's not much new to add to the already existing characters. They changed the Pre Time Skip Straw Hats quite a bit last time, taking time from other stuff. PW2 basically added like 22-25 new characters if you think of movesets as characters. It also added 20 support characters. 55-65 playable, would mean adding 18-28 characters not counting the fact that some may be half done already. My support list is too high but I'd consider it a good list to pick from. 10 of those support characters were in the last game and don't have to be changed.
Overall, my 30-40 guess would just be like 20-30 more support. I mean when you consider that they added like 22-25 new characters and 20 support in the second game, 18-28 characters and 20-30 more support, it doesn't seem that farfetched. Especially when you consider time and that some of those characters are almost ready to be playable.
