Alright, here's some playtesting footage of King Of Fighters XIII. Props to a friend on Facebook for posting this:
It essentially looks like King Of Fighters XII. I don't know if they are keeping the same exact sprites (which were actually low-res), or if they are redrawing them or upping the pixel count so it's actually high definition. Regardless, the fighting system looks the same, which is a good thing, because the new system rocks.