There is a fun theory going around that has to do with the Strawhats only having 11 crewmates and it matching well with the 11 "Zodiac" admirals (if the exist), Blackbeard, potentially Shank's crew, as well as potentially Im.
I'll start with the obvious. If Yamato joins, that would make 11 for Luffy.
- Blackbeard has 10 captains (1 unknown) and also himself
- Shanks has currently 10 main members, counting Rockstar. If Mihawk is meant to ally with Shanks for the EoS and fight Luffy, that's 11 members
- Each Admiral codename is based off the Chinese Zodiac so far. Akainu (dog), Aokiji (pheasant), Kizaru (monkey), Fujitora (tiger), Ryokugyu (bull), Chaton(pig), Momousagi (rabbit), leaving Horse, Snake, Dragon, Rat and Goat i believe. Aokiji is gone basically, and if he's not replaced, it leaves 11 Zodiac admirals. 7 of them would be VA's.
- Last one is a stretch, but Im, the Gorosei and Kong make 7 people that run the WG. One theory I've heard is that there are 4 WG operatives who command/run each of the blue's, while Kong mainly commands WG forces in Grandline/New World. We know there are unknown WG members, as Doflamingo talked to one at Marineford. Oda hid this persons face on purpose.
Just some fun things to think about. I do think many of these fights will be straight forward when the crew is complete.