Marchefelix we know next to nothing about the roster, nor do we know if this a new saga or a dream match. Ash's saga gave us 11 new characters to the series (Ash, Duo Lon, Shen Woo, Elisabeth, Oswald, Momoko, Mailin, Shion, Adelheid, Magaki, Mukai, Saiki) + raiden, Wha jai and kof xi on top gave us more characters from snkp large library of characters that we have not seen in a decade or from games with out sequels. They don't need to create new characters when they have plenty of properties under they own to use in this sequel. The US sport team is long due to return after not appearing in kof for more than 16 years. I do agree with you that some of teams are safe choice that we have seen forever like "art of fighting" just to name one.
Snkp as always been tinkering with the characters to make them fresh. Take Ralf in kof xii and xiii is my favorite rendition of the character the appearance along with a new move sets that made sense and he no longer felt cookie cutter with ralf kick, tackle, argentinian back breaker. Both Duo Lon and Elisabeth lost some moves and gained new one between kof xi and xii. All I am saying even if we keep seeing the same old characters between sequels, they are bound to have something new to set them apart. Took clark long enough to have armor on his signature move or "step" to close the distance.
The next trailer is set for next year. Hopefully they throw us some scraps from the development process while we wait. Concept art of characters and stages or interviews will do, just feed us.