Honestly given some of the stuff in this shadow drop, I'm inclined to think that the DLC was pre-planned long ago. The spirits, the addition of Joker in the banner, Mii costumes from 3rd parties being moved to DLC, could potentially (and I repeat potentially) indicate that the DLC newcomer selection started and finalized everything regarding negotiations even earlier that expected.
After reading some suff from
TheMightyP
, I think I possibly jumped the gun with the Mii costumes since I forgot about Akira. I think it could potentially mean characters from the companies appearing as DLC but nothing concrete yet (please only take it as a possibility).