Erdrick could still also be leakbait, because we know Square, according to people associated with them, likes to throw out leakbait. After all, the 4chan TGA leak got a lot of things right except for Smash info, and we were sure we were getting Metroid info. Instead, we got Joker. Plus, there is
Luigi The President
's argument when it comes to the Persona info and how long we've known about it. The fact that they know all of the details on Joker and Erdrick when Joker has only just started development, too, seems off when no one apparently knows DLC.
Temper your expectations, y'all. Keep them tempered.
That being said, as a Geno fan, I'm just going to presume it's Erdrick at this point and err on the side of pessimism.