@Scoliosis Jones: Your roster has 49 character slots, which goes with Sakurai's statement of not wanting to expand much of the roster. In that sense, it's a realistic bet. SSB64 had 12, Melee had 25 (approx. +100%) and Brawl had 35 (+40%) and this 49 roster would mean a consistent increase by 40%.
Secondly, series balance. Counting the DK, Yoshi and Wario series, the Mario series has a total of 10 characters, which is feasible, considering that's the biggest Nintendo franchise. While Paper Mario is debatable, K. Rool's inclusion is one big plus, since he's one of the major characters in the DK franchise and he's yet to be in Smash Bros. as a playable character.
The Legend of Zelda keeps the same characters as Melee and Brawl (counting Young Link and Toon Link as the same, since both share the same concept), which is conservative, but proves to contain all best known characters of the franchise: Link (both adult and young), Zelda and Ganon.
Metroid, given its low quantity of characters, is fine with just Samus and Ridley, the latter who's the main antagonist and one of the most requested characters for the fourth game. As with K. Rool, he's one of the few major Nintendo characters to not be playable in Smash Bros. yet, so his inclusion this time is highly justifiable.
Kirby and Pikmin don't really have much to add to Smash. Kirby's big 3 are already in and, despite Olimar not appearing in Pikmin 3, he's still the poster boy for the series, having appeared in the first two games.
Pokémon is playing safe and I wouldn't be surprised if the four characters in Brawl returned alongside Mewtwo, who could allude to Gen VI thanks to his new form. Lucario is still popular and was promoted for Black 2 / White 2, despite being from the previous generation.
The Kid Icarus series having a newcomer isn't farfetched given Uprising's success and popularity. Palutena is the likeliest choice as the newcomer, thanks to her consistent appearances throughout the three games of the series much like Pit.
Star Fox and F-Zero keeping the same characters as Brawl is expected, given that both series haven't received new games (excluding remakes or re-releases) in years. Same goes to EarthBound.
Fire Emblem is iffy... It's basically keeping all veterans while adding Chrom from the latest game. I see it happening, despite many disliking the idea.
Shulk, Isaac and Dillon aren't bad contenders and may well earn a spot on the roster, being the protagonists of lesser known, but acclaimed series overall. Little Mac's chances have improved since his series' revival and is one of the likeliest characters to make a playable appearance.7
On retro characters, I see Sakurai keeping the Ice Climbers, Mr. Game & Watch and R.O.B. given his comments on the older Nintendo series. Takamaru may well earn his spot (and possibly alongside other retro characters), much like the other three and Pit earned their spot in the previous Smash Bros. games.
Finally, the third parties. Given their status, I could say that anything is possible and we can't really have an accurate prediction regarding them, so I'm basing my opinion on other factors. I like Smash Bros. with a few non-Nintendo characters as they bring something different from the Nintendo characters and that is good for a varied roster. This said, if the four characters were in, I wouldn't mind at all. On the contrary, I would appreciate their inclusion.
Given that they only occupy less than 10% of the roster, I say that doesn't detract much from Smash's main concept as a Nintendo All-Star fighter. Third-parties? Yes, but in moderation. This is still a Nintendo game, after all, and this roster manages to capture that.
The DLC choices aren't bad, given that they consist of darkhorses and other lesser known characters. That's what I envision as a good objective for potential DLC.
All in all, this is a solid roster and would please me, even though it hasn't all the characters I want. After all, it's impossible to please everyone.
Rating: 9/10
And why are Shulk, Dillon and Isaac in both main roster and DLC roster?