DONT READ ALL THIS IF YOU ARE NOT UP WITH CHAPTER 370!!!
After reading chapter 370, i'm pretty sure Usop will rejoin the crew: right now i do think that he is already in the mood for rejoining, in truth from the time he did that speech to sanji and then put up the "sogeking" mask.
Therefore, i'm thinking that, even if he now wants to rejoin the crew (maybe he hasnt realized it yet, but his heart wants it, and his behaviour shows it), i'm guessing what will Luffy do: at a time like this, even if i'm sure Usop will rejoin, i'm guessing what should happen to make Luffy accept him a second time.
There is the "captain" speech Zoro did in the 35th volume: Luffy has to have a certain behaviour as captain. More, he is too much emotional right now about what happened, i dont think Oda can solve it too easily, not like a "Oh, what a mask, you are cool, just be friend again!", as usual.
So i'm really starting to wait for their meeting… i really dont know how will Luffy react when he will see Sogeking...
what do you think? :)