Characters: 32 to 43. If half the possibles make it, then that makes 37-38 characters and 0 clones. Don't forget Melee had 19 Characters and 6 Clones, so this is a vast improvement.
Mario - We are bound to see a new Mario character, probably Bowser Jr. or Waluigi. There's also chances for Geno (Although I strongly doubt this) and Paper Mario. I think two of these four will get in. Dr. Mario becomes a costume, but hopefully when you select it, he will still be slightly different, like in Melee.
Zelda - Three characters are not enough for this series, so we are bound to see a fourth, and possibly a fifth. Fill in the blanks yourself. Might see Young Link (or Wind Waker Link). Ganondorf has new moveset and uses sword.
Yoshi - I doubt we will see any more characters from Yoshi series, as there are already alot of Mario characters, and it isn't easy to tell the difference.
Donkey Kong - I assume we are bound to see another Monkey of some sort, most probably Diddy.
Wario - The characters in WarioWare are not really fighters, and there isn't much need for them.
Kirby - Possibility of King Dedede cannot be denied, but perhaps three characters for this series might be a tad too much in Sakurais eyes.
Metroid - Not very popular in Japan these days. There's a possibity of a second character (might be Ridley).
Pokemon - The original three will return. Pichu will be nerfed. A Pokemon will be used to represent 4th Gen, and possibly one to represent 3rd or 2nd gen.
Fire Emblem - Marth will stay, we will also get another Fire Emblem character. On the third slot, Roy might return (with a new moveset), or we may get a new character, or neither.
F-Zero: This series isn't as big as you think it may be, and also there isn't much need to give someone else a complete new moveset from ground up, like Captain Falcon. Plus, the fact that Samurai Goroh is a Assist Trophy makes me strongly doubt another F-Zero character. Don;t forget this is just a racing series.
Star Fox - Falco gets new moveset, possibility of another Star Fox character is there.
Earthbound - Not big outside Japan (yet?). Ness will return, Possibility of second Earthbound character.
Retro - I don't see any reason for Nintendo to remove Ice Climbers and Game & Watch. They have unique movesets. Along with Pit we may see another Retro character (Balloon Fighter perhaps?)
Other Nintendo - Possibility of other Nintendo Series, like Pikmin or Animal Crossing, or perhaps something totally new. I think we are bound to see one familiar new series make a debut in Smash, with the possibility of a second.
3rd Party - We will definietly get at least one more 3rd Party, and possibly a third. The candidates are Sonic, Mega Man and Bomberman, but don't always expect the obvious.