Melee had 26

Brawl 36 

WiiU/3ds has 22 until now 

Do you think they will be more than Brawl ? I don´t think so :/ 

I predict that we will not reach the 30 ... -_-

MIyamoto 2013 : 

"I can answer that: no. We don’t have the time to fully recreate every single character who’s been in Smash Bros at this point," Sakurai explained.

"Adding new characters is not a simple addition – it’s really multiplication. The amount of work, adding a character is multiplied and becomes bigger and bigger as you go. We can’t because of the amount of work it takes. However, I do believe I understand that each character has its own set of fans out there who really like that character.

"So we’re not going to cut characters out of the way, we’re going to put in as many characters as we can, we really want to do that, because it's good for the fans and good for all of us. But in the event that we do have to cut some characters, I’d like to apologise in advance to those fans."

Didn't Brawl have 35?

Anyway, I expect about 40.

For some reason I remember Sakurai saying the roster would be smaller this time. I say the more chars the better, but if that's true I'm guessing somewhere between Melee & Brawl.

I think we will at least get 35. There are already 4 new characters, and I cannot see more than 4 characters being cut from Brawl (maybe Wolf and Pokemon Trainer). Along with the fact that some characters might be coming back from Melee makes me fear that some awesome Brawl characters might get cut out. I still think that at the end we will see a number closer to 40.

if i had 2 guess they will dump jigglypuff

Whattt? 22 are shown and there are obviously several missing that will return (100% returning = Diddy Kong+Yoshi+Jigglypuff+Ness+Captain Falcon+Zero Suit Samus+Metaknight+Ice Climbers)

Thats 30 right there + There will be at least another 6-10 new comers.

I think rosalina replaces ice climbers. Did you read Miyamoto´s quote ? 

35+ only because this going to be a heavy focus on fighting.

Yes, they are cutting/replacing characters, not taking out half the roster. The characters I listed above represents a franchise or is a huge part of it. The roster will be anywhere between 38-45 imo. there are 22 with no release date. Unless you want to make a bet with me? I bet its over 30 playable characters