Personally, although I love XIII, I don't think they should release an updated version. I'd rather see them utilize their resources to create a new KoF with what we want(characters, stages, intros, more moves, etc.).
KoF XIV should do what 98UM and 2002UM did. Add ALL the characters and bosses from the last saga, use one of the gameplay engines used(in this case it would be XIII's, I don't see 2003's/XI's or XII's returning.), add Rugal, Goenitz, and the New Face Team, and viola! You got yourself one hell of a dream match!
Problem with that is that SNK should create a big amount of sprites to make this happen
-Tizoc
-Jhun
-Chang
-Gato
-Yamazaki
-Blue Mary
-Shingo
-Hinako
-Malin
-Whip
-Chizuru
-Adhelaid
-Mukai
-Oswald
-Duck King
-Vanessa
-Ramon
-Eiji
-Kasumi
-Jenet
-Momoko
-Gai
-Silber
-Hayate
-Jyazu
-Shion
-Magaki
Then if SNK does it for the lols, they could add the new blood team, the PS2 exclusives, and maybe filling some spaces to make the roster with some sense, but without, those extras, you are already doing more sprites than SNKP has made just for one game (considering that for XII they release 22 and in XIII like 13 more that even were developed just for XII
Knowing how tight is SNK with money, is almost impossible to dream, will be cool sure, but it will take between 2 or 3 years to make an UM version of the ash saga