*sigh*
On the one hand, Ness' position may be usurped by Lucas.
* His special moves are the exact same as Ness' were
* Sakurai was planning on replacing Ness in Melee anyways. Why not in Brawl?
* If Ness was in, why has the only inclution of his name been attached with "up until now" instead of "in the previous games"?
On the other hand, Ness may be fighting along side Lucas.
* Sakurai has Ness in his mind, at least. Why mention Ness at all if he wasn't going to be in?
(Counter point: He was merely informing of his absence, but in a sneaky way)
* Ness may come back with a different moveset entirely. Weren't those PK powers not his anyways?
Now then...now that that's over...
Capitan Falcon: The only rep of his game. His quick movements and fire-based techniques (*cough* FALCON PUNCH *cough*), along with the fact that he has a symbol already for Brawl, his apperance is assured. Chances: 99.9% (Sakurai may pull a fast one on us.)
Luigi: ....Do I even need to say it? Luigi has so much potential, it's WAAAAAY too easy to put him in without clone status. Chances: 100%
Jigglypuff: I dunno. Jigglypuff's got an original moveset, is fluffy, and a Pokemon. However, despite her rabid fans, they've sort of dwindled in favor of other Pokemon like Lucario or Blaziken, or for different characters in general like Geno or Capitan Olimar. As for Sakurai...I dunno his opinion. The David Hayder thing could be subject to debate, however, and could definitly be either a foreshadow of Jiggly's return, or merely an "off-the-top-of-my-head" thing. Chances: 75%
Of course, this is all my opinion formed through facts that I believe as true. If you think I am wrong, you may come to my house and say "I am very much against your opinion, my good sir. Good day to you." or something like that.