If the roster hadn't been leaked via the select screen capture, and if the street date had not been broken, it's possible that folks would still be speculating who the hooded figure from the story trailer is.
As of this point, the only un-revealed character is Frost, and it seems NRS *really* wanted her to be a surprise.
It's tradition since MK9 for there to be a Sub Zero spin-off as a secret fighter.
You know, you're kind of right. I don't believe Cyber Sub-Zero was ever shown before MK9's launch, I remember him being leaked a few days before the game's release.