A Mario rep surely isn't given. I think there's a reason that there was even one cut off from Melee to Brawl. Sakurai has stated he's very careful about adding too many characters of one franchise, referring specifically to Mario iirc, I'll try and find the source if you'd like me to. I think the Mario series is complete, every other possibility is just a cherry on top. Just look at it, we have Bowser who kidnaps Peach, and Mario and Luigi goes to save her. The end, that's the majority of Mario games right there. Same for Zelda, I'm content with the Triforce trio, because it completes the series, an extra Link always just felt like extra material.
And don't expect too many new characters, else there'd have to be cuts to compensate, just like Toon Link, Snake, Wolf and Lucario were cut on this roster. I think the number of newcomers and the roster itself is pretty realistic (with the exception of Krystal replacing Wolf,) but I still don't believe that it's a legit leak.
My only quarrels with this roster is cutting Wolf for Krystal, cutting Snake, and Dixie getting in over K. Rool. Still, I'd be satisfied myself with Brawl's roster but just with Ridley, K. Rool, Mega Man and Mewtwo on it, so I'm not super hard to please either way.