I'm pretty confident to say that Iori will be on the next update for sure. He's one of the main flame users in the kof cast. Also hope they will update more colors for characters. So far you can only buy 4 alt colors.
Well, if you look at the description, now we have 13 char.. plus october update 6 char so... 13+6=19 char But, try look at the description once more, it said "a total of 20 character" (one secret char?)
http://www.gamefaqs.com/iphone/636128-the-king-of-fighters-i-002 --- Xbox 360, Best Console Ever
"The 13 fighters, including protagonists Kyo Kusanagi, K’ and Ash Crimson are joined by Billy Kane from “Fatal Fury”! But that’s not all!6 additional characters will be available to download for free by October, 2011 for a total of 20 characters!" --- Xbox 360, Best Console Ever