@fana:
The fight against BB more likely will involve the whole world and I can't think of a plausible way for every member of the SH crew (expecially the weaker ones) to conveniently get a direct fight against a BB captain with all the other characters that would also be present in that war.
Its a shonen. Every main member will get a final 1 on 1. Even if Oda cuts a thousand other corners to finish the series quicker I can't see him not paying off that part of things.
They have a bajillion allied to deal with all of BB's allies. Plus the marines and revos and pacifistas and ancient weapons and whatever else ends up on the table.
@Shiebs:
I'm also very interested in what Robby thinks, since he's been a die hard advocate of the 10 crewmembers
The last couple chapters Oda's been doing stuff that makes his "done in 5 years" announcement seem a bit more genuine. Basically cramming a huge ammount of Roger flashback into two chapters that I always expected to take months a little closer to the end.
I still don't think he can do it in 5 years unless he leaves out basically all fighting from here on, but 8 seems about right at this point, rather than the 10+ it seemed like he might still need.
So if he's pushing ahead and streamlining, then count Vivi and call it a day and that's perfectly fine and still fits the number of BB's to deal with and Luffy's original words.
Otherwise, after Wano wraps in a year, the new person better show up FAST or else there's not much point. Which wouldn't be unprecedented. After Robin we went ( at the time) half the series before Franky joined, and then Brook showed up a week or two later and had a relatively short joining arc.
I still think there needs to be one more suprise island we know nothign about, because knowing the entire path from Fishman Island to Raftel means we basically knew the route of the entire journey except for Punk Hazard in advance by a decade, and that feels really un-Oda.
Or, you know, Oda loves vikings, so maybe they find someone on Elbaf.
Regardless, the series feels new like it will ultimately be a little shorter than it seemed it might be even just a few months ago, so its harder to say anything as surely or tell what kind of corners Oda might end up cutting.
@Shiebs:
also I'm sure Robby will say something about her hair color being far to similar to Franky's to be an official member
Franky's been bald since the timeskip.
His hand picked VA means he's definitely a disqualifier for Mr. 2 joining tho.