The I'll Face Myself remix was a pleasant surprise; it's kind of a P4 medley. The first thing I did after finally updating the game was check out the new songs and add them to my favorites lol. Joker is fun; he's worth learning and I'm glad he doesn't seem... overtuned, for lack of a better word.
As far as Playstation-esque reps go, I think Heihachi from Tekken seems likely. Here's why:
-Nintendo's friendly relationship with Namco Bandai, and the latter's involvement with Smash.
-Tekken's popularity and influence on the 3D fighting game genre. It's an iconic and relevant fighter that rivals Street Fighter.
-Sakurai considered him in the past, but found him too difficult to implement. It's a new game, so chances are, he can work around it by now (see: Ridley, e.g.)
-His Mii costume is suspiciously absent.
-His Japanese VA died; it'd be a good tribute.
-He's already crossed paths with Ryu and Ken (and he has a history with Akuma), a Final Fantasy rep, a Metal Gear character, and he's literally been in the same game as Link. Aside from that, he fights robots, kangaroos, dinosaurs, ninjas, etc. on the regular; he'd fit perfectly in Smash. It helps that he's already been in a game where he beat up characters dressed like Mario, Peach, Samus, etc.