Daisy? Heck no.
While I kinda want Smash to be a bit less of a sausagefest, there aren't a whole lot of female characters that I know of that really deserve/have a chance to be in SSB.
Off the top of my head, Lyn and Dixie Kong are probably the only characters that are interesting enough and have the name recognition to make an appearance. There are plenty of other characters that are cool/ important that just don't have the name recognition to make an appearance.
Edit:
Just for fun, I decided to categorize the characters in Brawl according to their genders:
Male Characters:
[COLLAPSE="Male"]Mario, Luigi, Wario, DK, Diddy Kong, Bowser, Ness, Lucas, Yoshi, Fox, Falco, Wolf, Captain Falcon, Marth, Ike, Olimar, Link, Toon Link, Ganondorf, Popo, Kirby, King Dedede, Meta Knight, Pit, Snake, Sonic, Mr. Game & Watch
Total: 27[/COLLAPSE] [COLLAPSE="Female"]Samus/ZSS, Peach, Zelda/Sheik, Nana
Total: 4[/COLLAPSE] [COLLAPSE="Gender Ambiguous(meaning we don't know their gender)"]Pikachu, Jigglypuff, Lucario, All PT Pokemon
Total: 6 if you count PT pokemon individually[/COLLAPSE] [COLLAPSE="No gender"]ROB
Total:1[/COLLAPSE]
If we count the "Fallen Five":
[COLLAPSE="Male"]Doc, Young Link, Roy
Total:3[/COLLAPSE] [COLLAPSE="Ambiguous"]Pichu
Total:1[/COLLAPSE] [COLLAPSE="No Gender"]Mewtwo(Almost all Legendaries have no gender)
Total: 1[/COLLAPSE]