The nakama point is very….VERY up in the air. It all depends on how Oda wants the series to work for him.
Way back when, in 2002, he said a nakama would die 「亡くなる」.
Then he confirmed this again in 2003. I witnessed this event.
From then speculation ran wild. Yes, he said 'die', but did he REALLY mean 'die'? Did he mean leave? Would it be Tonjit? (remember those days?) Would it be Chopper from the Davy Back? Would it be KAKU!? NO! Paulie! No wait! Maybe Lulu? Perhaps Tileston? NO WAIT! ICEBURG!!?? BACK TO PAULIE!!????
And then Franky or so it (very likely) seems.
Oda's been jerking us around for a long time on the issue and I bet he's been loving every minute of it, not to mention what hints we've had at Merry's importance to the crew. Remember Merry's cover page between cover stories? Then we have further confirmation of Merry's presence as a 'member' through how the crew refers to it.
And so the ultimate question is, can Oda handle 10 crew members? Keep in mind, each time he adds a new crew member, there's a handful of weak points the crew HAD that they no longer have, making his weakening of them as a crew all the more difficult. (especially when Robin joined holy fuck)
It's a very curious question and we may not know up until the end but Oda seems to be leaning towards counting the ship as a member of the crew. Whether this is to give him a buffer or if he has a bigger picture in mind to surprise us remains to be seen.
But two things are for certain.
Luffy said 10 so there will be 10 somehow.
Luffy wants a Musician so we're gettin' a Musician.
This much we can count on.