His text box name says: 有里 湊
Which translates to Arisato Minato
If I had to guess, it's a placeholder name for the trailer. I'm betting that the protagonists will still be player-named in Persona Q. I'm digging around on the updated site, and the graphics related to both Makoto Yuki and Yu Narukami are "p3_hero_main.png" and "p4_hero_main.png," respectively. Narukami has been the canon name for both The Animation and Arena, and yet he isn't named as such in the site assets, so I don't think the P3 protagonist will be either Makoto Yuki or Minato Arisato.
Obviously this isn't proof, but in P4G's Shadow World opening Narukami is called "Hero" and you had to name him, and on Persona 4 Dancing All Night's site he's called "Persona 4 Hero" as well. I'm not sure why they'd choose to name him in certain media and not others, but I still think this means we'll be naming him and the P3 Hero in these games. We'll see, though.
EDIT: There are some nice almost full-body renders on the updated site, too. So if anyone wants an avatar for one of the currently available characters (Makoto, Mitsuru, Akihiko, Shinjiro, Narukami, Chie, Yosuke, Yukiko, Zen, and Rei) please let me know. Hopefully they'll add the others soon, as I know a couple of people who really want a good Naoto one, so I'll be keeping an eye on the site and ripping what I can.)