How many hearts...

Will be "awakened" in the next KH game?
all the hearts that are trapped whether it be in darkness or trapped inside Sora, or Xeranort.
I personally think all the Hearts that are trapped inside Sora will be awakened, and those trapped by Xeranort will be freed, and returned to their bodies just as Axel/Lea was.(Im counting nobodies hearts as well, Namine,Xion ect)

how many do you think will be awakened if any?

 

I'm hoping that Isa's heart will be freed. Saix is one of my favorite characters and I want his "true" self to have at least a semblance of happiness in the end.

Honestly if the Kh-team wants Kingdom Hearts 3 to be the end of the Xehanort Saga then it only makes sense if everyone who is "trapped" (Terra, Aqua, Ven, Xion, Roxas, possibly Isa [and Braig for fairness]) gets "freed" and we'll get a bit gushy happy ending that will stay happy until the next big crisis decides to randomly appear.

So to directly answer the question, 5 "for sure", possibly more if Nomura decides that Isa deserves to become human and get his friend Lea back, Braig if he decides if he can be redeemed in some obscure way (Not likely imo), and Vanitas if Nomura wants him to become a "real boy" for some other reason.

 

Hard to say.
Before an answer is given we need a well defined term for "awakened" since that is not the express term that has been used in the series from what I recall.
If we are going by, and I'm assuming this is what you mean, all hearts that are in some form of distress being rescued, the only ones that I can really think of are Ven and Terra.

Aquas heart was never separated from her body, so she doesn't count.

Xion ceased to exist, so theoretically she shouldn't be counted, but I can easily see (as much as I don't want this to happen, and as terrible as I think it would be) he being brought back through some hokey explanation just to satisfy fans and make her seem somewhat validated. (even though she doesn't have a heart so she shouldn't even be up for debate)

Namine doesn't need rescuing. She is perfectly content right inside Kairi, that's where she belongs, her story ended at the end of II along with Roxas.

 

I think it would be cool if Roxas, Namine, and Xion could all come back as their own characters. I know they're part of Sora and Kairi, but I miss them!!