My Guess for the next Nakama are :

The next Nakama..
Should it be TWO, THREE or FOUR..?

So..
My guess for the next Nakama are:

If TWO Nakama (I think it is more than TWO) :
i) Jinbe
ii) Nefertari Vivi

What were the reason for each of them..?
i) Luffy ask both of them to join SH..
ii) Both answer to Luffy that they got important thing to settle down.. Jinbe need to tell Big Mom he want to leave & Vivi want to take care of her kingdom since she is a princess..
iii) Jinbe help Luffy and Ace and always care for Luffy..
iv) Zoro asked Luffy to kidnap Vivi after Alabasta Saga..

I got more information for Vivi..
But I will exclusively make one POST for her.. lol

If THREE Nakama:
i) & ii) still the same person
iii) Gastino (Ceaser)

What the reason for Gastino..?
i) He's a Logia DF user.. Maybe SH will make use of his Gas Gas ability..
ii) He need the second chances.. Yeah he done evil thing in the past just to become the best scientist.. Maybe if he was given the space and time and also respect.. He will become even greater than Vegapunk..
iii) Changing his name to Gastino makes him a new identity.. Maybe with new fresh identity.. He will become a new guy..
iv) His role as scientist will be the plus point for SH.. He will help Chopper with medicine, help Usopp with weapon (inventor) & help Franky with shipwright maybe make used of Cola for fuel up Thousand Sunny..

If FOUR Nakama:
i), ii) & iii) still the same person
iv) Momonosuke

What the reason for Momonosuke..?
i) He will become as Lord Oden who sailed with WhiteBeard (Yonko) & Roger (Pirate King)..
ii) He got an artificial DF, it will makes the crew more havoc with all type of DF..
iii) Maybe Luffy & Momonosuke will learn to control Voice Of All Thing (VOAT)..
iv) He will lead the SH's grand fleet under Kouzuki Clan & Minkmen..

What are the characters that you guys pick..?
Share with me your thought.. ^^
Please read other theory that I Post in my blog and comment as much as you guys want..

Let spread the love for One Piece.. ^^

But there's are Character that we should considered too..
i) Princess Shirahoshi the mermaid (Poseidon) - Luffy promise to bring her to human's forest
ii) Carrot - She's amazing character.. The one next to Vivi if Vivi is not the next female nakama.. lol
iii) Pekoms - I bet he's loyal to Big Mom..
iv) Wadatsumi - I think Luffy need giant as his nakama too.. Maybe Wadatsumi will be consider as giant..

How about someone as caliber as Jinbe (ex-warlord) as Luffy next's Nakama or maybe Ally
i) X-Drake
ii) Hancock
iii) Mihawk
iv) Bonnie
v) Urounge the monk