Here's the twist, they aren't. (Seriously)
This is true.
In fact, according to the KOF Tenth anniversary from years ago, it was confirmed that basically EVERYBODY is still in "alive" status, except for Rugal, Goenitz, Igniz and Both Zero's.
And as we know now, K9999 got retconned away by his replacement "Nameless", and I'd like to think all those Kusanagi clones (except Kusanagi), are all deactivated.
So, the quick answer is that it gives SNK all the leeway they want to be able to bring back practically any one they want. At least they don't have to say anything to the effect of "Oh, he/she got better!"
Any way, I love the look on Kyo's MAX DM, and Takuma and Vice complete their respective teams (which I also like).
Is that new version of Mu Shiki for Kyo, or what...?