I would love to see a Dream Match of Ash Saga just like kof98 and kof02 for kofxv, but I guess that is impossible
SNK might still be ongoing with the Verse saga. My guess is Antonov has become a playable character and join with two characters (maybe Mian and Sylvie?). Ash might team up with Elisabeth and Shen/Kukri since Ash has returned as shown in the Official Invitation Team ending in kof14.
Edit: I almost forgot that since Verse was defeated in kof14 and released the trap souls of Rugal, Orochi, Gaidel, Krizalid, Igniz, Ash and Rashojin Mizuki, there might be possibility that they will appear in kofxv where the protagonists such as Kyo and K' will have to deal with their past enemies again except for Orochi since he is sealed again in iori's kof14 ending. Gaidel might be new character who is Leona's father, father and daughter reunion
Veterans Day