There have been four games between KH2 and KH3People have been saying this since long before any interview. The FF characters have had pretty much no involvement in the games since KH2 came out 13 years ago. The series has completely moved beyond them by this point.
Of those. Only DDD and 358/2 Days didn't have FF characters (And even DDD supplemented them with another franchise in TWEWY)
BBS had Zack, who plays a big role in Olympus
And coded is a KH1 rehash