It seems like the consensus that the # of available slots in a location is tied to the # of invites going out to that area of the world.
I don't think this is the case for a few reasons:
1. If they knew how many people from which areas were going to get invited, they'd send all the invites out at once, vice in two waves
2. There is nothing binding about the location at which you interview. I am equidistant betwen two international interview locations and HBS has no way of knowing (afaik) which one I'll pick (i don't think the app calls for identifying a location, right?)
3. They have no idea who'll be able to even make it and who won't. This is evidenced by the numerous skype slots they have.
My point is try not to succumb too much to forum-induced neurosis and stress yourself out unnecessarily by developing complex theories on why you are or aren't going to get an invite.
Best of luck to everyone on Wednesday!