The outlay of the situation is odd, in a way, that I still can't imagine where Oda wants to go with it. If BB were to fight Garp and the old marine would loose, I very well could imagine Oda using this to set up Luffy against BB. With Aokiji as his current opponent however, I still am not sure where he wants to lead us - or what purpose this serves.
You also could say - I cannot imagine what consequences Oda will draw out of the current setup between Aokiji and Garp and which character it will affect most.
As for the matter of the 11th crew member: We actually have one very well fitting candidate for the last seat on the sunny. The gorowase fits with his DF perfectly. He is someone, who actually fits Jinbe's description in chapter 979 of the post, the last member of the SHP needs to take up, very well: "[...] the key will be having someone who can calmly observe the state of the battle.". And this person is currently even doing so and observing the state of the battle and even gives analytical output, so Luffy and Zolo can act accordingly. He had ample introduction during Water 7 and Enies Lobby and was fleshed out there. Now on Egghead, we see him questioning the WG's decision and even ignoring given orders, which is really strange since he we know him differently - people even call him the loyal dog of the WG. The whole crew knows him and had at least once interacted with him. Him becoming the last crew member would not even mean Oda would need to flesh out the character in the upcoming arcs anymore - because he did that already.
Even if I am the only one here that thinks so - Lucci is actually the most obvious choice for the last place on the Sunny.