The more I think about it, the more I feel like Sakurai will come out and surprise us all with 50 characters. This Brawl team has more of EVERYTHING than the Melee team did...they had a lot more time, and ALREADY had the Melee work to build from, literally. Meaning that all the characters in Melee were pretty much "set" for Brawl, aside from little touch ups here and there of course.
It's not only the fact that the Melee team had to create 14 new characters in the span of a year (supposedly), but they couldn't use the SSB original engine in the first place. So they had to start off brand new. And STILL managed to fit 26 characters in there...although 19 of them were truly original.
So if Melee really DID only have one year to work and Brawl has had over two years then...they should at least be able to double the total. Seriously.
Aaaaaaaand finally, my final points...the characters themselves.
Right now, we know of 23 characters. I think a lot of people fail to realize this.
WE ALREADY HAVE ALMOST AS MANY CHARACTERS ANNOUNCED FOR BRAWL AS THERE ARE IN MELEE.
I really think this is just the tip of the iceberg. And that isn't even counting Melee vets that are sure to return...discounting all clones (including Falco >.>) other than Ganondorf, who has already been "announced", we have 31 characters on our Brawl roster.
The eight I'm referring to are Luigi, Jigglypuff, Captain Falcon, Ness, (the original four hiddens), Ganondorf, Marth, Mewtwo, and Game & Watch.
You can infer G&W is in the game due to the whole icon links thing on Dojo.
Apparently, this is the icon of his little G&W series.
http://www.smashbros.com/en_us/images/icon/world_b_13.gif
The reason people infer this is because it is the only icon that hasn't been revealed yet that isn't after the last icon...and it's squished between the Fire Emblem and Ice Climber icons. Which means that it must be a veteran icon...and G&W is the only one left. Makes sense.
Most people agree that Marth will return. Screw Ike, he plays completely differently. In addition, I think there is a Fire Emblem remake that features Marth, so he is still relevant in Nintendo-lore.
Mewtwo...well, there really isn't much to back him up. But I'm confident he'll return if G&W will.
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He is unique and totally badass. And if the development team can make Bowser awesome in Brawl, then I'm sure they could shore Mewtwo up...and he is THE greatest (Pokemon) villain in the Poke-universe, even after all these years. Mewtwo could play an interesting role in the Emissary...
Yeah, those are my points. So assuming all non-clone vets will return from Melee (which I'm quite sure of), we know of 31 characters in Brawl already. And to think that there are only 5 or 10 characters left to unveil is RIDICULOUS. I'd say 15-20....putting the total at 45-50. :D