Namco: Due to the director they have onboard for Smash Brothers 4, it is extremely likely that one or two characters will make it in from the Tales series. Most likely Tales of Symphonia, Tales of the Abyss, and Tales of Vesperia.
In all likelihood, it will be one of the main characters from those games, so we have Lloyd Irving
Luke Fon Fabre and Yuri Lowell
But just as a blind guess, Lloyd and Yuri have a higher chance than Luke. And with Yuri being in the Project X Zone game, he has an advantage over Lloyd.
If they are going to cross over any other series, it will have to come by Popular Demand. Ace Combat has a low chance at this, as it is not that well known outside of it’s fanbase.
Bandai: After looking around for a bit, I discovered that Bandai, along with being a video game publisher, was also a Toy Maker and Anime/Manga Distributor. Thus most of their Video Games also reflect the fact that they mainly do licensed video games.
However, as they even said in regards to Smash Brothers “I wonder why nobody has asked about Gundam that much [as opposed to Tekken]?”
Anyways, Bandai does not have that many non-licensed games, so it is hard to speculate realistically what they would put in the game.
Now then, the other co-director that was added worked on nearly all of the Metal Gear Solid Games, and those make up about half of his game producing career. Solid Snake has a good chance of being invited back in.
Now then, with Katies “Crossover Limit Prediction” of about 3 series, that leaves one slot left open, and likely that will be influenced by a few things:
~Bandai doesn’t have that much material, so unless if they really do get Gundam into the game they will pass this ticket over to Namco.
~Namco has plenty of popular game series, however they will probably want a fan vote at some point or another. Right now Tekken has the spotlight, though a character from Soul Caliber, or (sigh) PacMan may make it in also.