English translations will vary, but the legitimate ones going off the japanese original have Luffy say he wanted ten FRIENDS, not just "ten total".
Blackbeard's group now has 10, plus BB. (But not counting Stronger the horse.)
Oda loves soccer and he's made references to the Strawhats being such a team, and soccer has 11 players.
It was confirmed in some interview recently (databook? I forget) that "two will join in fast succession."
There's other stuff but those are the highlights off the top of my head.
Assuming that is correct (If it's from a data book then that could be sketchy), that would mean we would get Jimbe and someone else pretty quickly. So either one of two things could then be assumed, either we get Jimbe joining then the other one comes shortly after that, or we get another crew mate and Jimbe joins shortly after that.
I have one question that pertains to Robin, if she was originally not going to be a crew mate, then did Oda have plans for a different crew mate? Assuming the 11 crew members were going to be correct, did Oda have a plan for a different character, or as far as the crew is concerned, does he wait until he has an idea then insert that character into an arc?
If that's just the stuff on the top of your head for how the crew would be eleven total, that's a strong case. I still stand by the statement at the beginning of the series not being good enough, cause how much things have changed since then. I'm still skeptical on the Black Beard front as well, but the fact that there is the soccer part along with interviews, it's a number of alarms going off that it indeed would be the case. I think deep down I'm hoping there is no more crew mates because it feels late in the game to have a new one. Brook still hasn't had a lot of time and Jimbe needs to join and have more time to shine with the crew.