I'm just going to say this. There'll be another mascot brawler but with more emphasis on it just being a rumble between various different characters (so they won't market it as some Playstation legacy game), and I don't believe you're going to get an 'All-Stars' sequel. They won't associate it with that. It'll be a different name.
The big mistake with All-Stars was releasing it like they did, and on the PS3. They should have saved it as a launch window title for the PS4. It would have given it more attention, and potentially more opportunity for success. It was sent to die with just poor decisions surrounding it.