The forum for expectations of the character hinted in Persona 3 Portable, Vincent. I believe he'll be a more secondary character, as in not in your party, but I think he's a character in P5. I don't think he'll be in your party because he's over 30, and going of interviews the team likes the fact that you're playing as high school students.

Huh... interesting. 
 
Don't really have anything else to say, don't like speculating on these things too much before anything is revealed by the developers themselves. But I am wondering right now whereabouts Persona 5 will take place on the timeline... whether these are issues he's had to deal with in the past in a social link with someone in P5, or whether this will be the focus of his Social Link in the future.

He looks like the doctor in Trauma team.