Let me put this into perspective for a moment by focusing solely on Nintendo characters for the moment. As most everyone is aware of upon the completion of Super Smash Bros. Brawl Masahiro Sakurai was quoted in an interview as saying that apart from Pikmin there were not many new character driven Nintendo IP's to choose from. (I believe with Nintendo Power, might have been IGN). This statement was in spite of acknowledging the existence of series like Golden Sun, Custom Robo, Jill Drozer, Legendary Starfy, Sin and Punishment, Nintendo Wars, and other obscure series; yet in spite of this he only felt compelled to include Captain Olimar for a new series. Why is this? That is a question that was asked here during that time, and remains a question to this day. Personally I have come to align with the line of thinking that says that, as far as it holds true now, first party Nintendo IP's hold the advantage over second party series. Second party series such as those listed previously have generally been less prominent, and this could be part of the problem. Out of all of the Assist Trophy characters listed on the DOJO only Saki Amamiya even appeared to have the slightest bit of interest by Sakurai (perhaps in part to his own affection towards arcade shoot em ups).
So what is my point? My premise is very simple. I do not think many of the second party characters are going to be in any better of a position than they were years ago. When you remove them from the equation what else is left? People complain whenever the idea to add more characters to existing series are brought up. It challenges the status quo of what is an acceptable limit of each series. Kirby is complete, Mother is complete, Star Fox is complete, Zelda is complete, Mario needs no more than five characters, so on and so forth. Okay, so what else then? How many new first party IP's are there that can offer a character to choose from? More poignantly series that are not going to wind up in the same category as Nintendogs or Animal Crossing? Only Xenoblade and the Wii series come to mind. Sakurai certainly isn't going to add a bunch of random retro characters to make up for perceived deficiency in the roster. What more do people want then?
One positive out of my rambling is that because of the pool being so thin it is not so farfetched to believe cuts will be minimal in the next game. The flipside is, there probably will not be a large increase of new characters either. It might be a good thing Sakurai is not challenged to just expand the roster because with the way things are headed the next game might just have the lowest roster increase in the series bar guest characters or Sakurai's new found love for B-tier series.
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