That'd probably be even worse. New title, new character, yet still taking up Nomura's time? The fans wanting the next major game (numbered titles) would rage. Forever.
You're absolutely right about the fans, but KH is going to get
really stale really fast if Nomura cranks out main games at the pace all the fans want (I probably shouldn't say
all the fans; it's just the outspoken ones who're screaming "KH3!1!1!1!1!"). Sora can only stay 16 for so long, and then the series is going to have to retire because things are getting ridiculous and Nomura refuses to dump Sora. Plus, there are only so many Disney worlds that would be interesting to explore in an action-RPG game. And we all know everyone expects several new worlds in every main title. And that's ignoring the fact that there's no way that the development team is going to be available to make three or more straight main titles; there are going to haveto be some side/bridge/spin-off games. Seriously, if this series lasts past six main titles, it'll be a laughing stock as far as plot goes. Might as well milk it from as many angles as possible while it lasts.
Just the other day I posted somewhere that I thought a side series for Wii would be fitting, because the un-orthodox controls would probably warrant a unique(ish) battle system. I think a series chronicling the Keyblade Wars (with a new main character) could be pretty darn cool. And while I don't know if a new series title would be good, I don't think the title
Keyblade Wars would really put off too many fans. As soon as Keyblade Wars appeared in KH2's ending everybody started throwing it all over the place and saying KHIII would be the Keyblade Wars. I think people like the phrase. : )
And I know KH "is Sora's story" and all that, but really, who gives a crap about Sora? He's one of the worst Gary Stues I've ever seen, and since the KH series as a whole isn't very good at creating truly memorable characters, I think a fresh cast could do the series some good. Look at BbS; while it wasn't an entirely new cast, it was pretty close, and everyone considers it one of the best games as far as characters and plot are concerned. Going backwards in time gives Nomura more chances to throw out unique and creative ideas he simply couldn't do with existing characters and existing relationships. And while Sora wouldn't be the main character in a KW side series, I'm sure Nomura could find other ways to tie the Keyblade Wars to the main series(He could even make the hero look like Sora, because there never seem to be enough Soras[/sarcasm]).
All in all, if Nomura's going to milk the KH series (which he is; the next saga is proof), then he darn well better do a good job of it. Adding new characters and side plots could go a long way towards preserving the series and keeping long-time fans' interest. I for one am going to be sick of playing as Sora all the time by at least KH5.