Let's be realistic here people.
At this point, Sakurai is just doing what he wants most of all. I think the only DLC character that's "likely" is Wolf. Everything else is up in the air.
I don't know how many ballot characters we'll see, but 2 (at most 3) seems like a reasonable number.
As far as who's likely, let's instead approach this from a more logical standpoint, and see who's NOT likely or look at opposition all candidates face rather than circlejerk out fantasies over who we wanna see the most and coming up with some arbitrary percentile.
Newcomers:
Inkling - with content for them already being in the game, I think they've got a better chance at showing up in Smash 5, especially since Splatoon is basically guaranteed a sequel given its global success.
Impa - not unless she scores high in the ballots. However, given her recent rise in recgnition and popularity, I can see something happening for the next game.
Chrom - not happening, not even next game
Elma (yes, the girl from Xenoblade X) - if we're ever gonna see another Xeno character added to Smash, it'll without a doubt be her. However, I can only see it happening as DLC for now, and she kinda falls into the same paradox as the Inklings, where she was released too late to make Smash 4, and too early to be relevant by Smash 5. It's likely that Xenoblade X will get some direct sequels from what I've heard about the story of that game, and if so, she's a strong conteder for Smash 5, possibly replacing Shulk, on the other hand though, XenoX was met with some strong criticism from Japanese fans, so who knows.
Waluigi, Lyn, Ashley, Zero, Tingle, Ridley, or any other character already in the game as an Assist Trophy, Stage Boss, or Mii outfit - try again. Not saying it can't happen, but the chances of it happening are incredibly slim tbh, their content is already in the game to serve as a form of representation for that character. That was the whole point of ATs, Miis, and Bosses.
Captain Toad and Bandana Dee - I don't see either happening this game, perhaps its personal bias, but compared to the other contenders they are among the most weak and least popular.
The Monster Hunter: I see this a lot, but not only is it dumb cause Ryu is already in, but CAPCOM HAS OFFICIALLY SAID THEY DON'T WANNA SEE HIM IN ANY CROSSOVER TITLE EVER PERIOD AS IT DEFEATS THE PURPOSE OF A CUSTOMIZABLE CHARACTER. Yes, I know there are other characters like that, but you don't understand what MH is about if you're seriously comparing other custom characters to MH. AND, those devs have never gone out to state they don't wanna see it happening.
Chorus Kids: I forgot these existed tbh. Whether or not you choose to believe the leaks were legit kinda plays into it all. If Sakurai throws a curveball, this might be it.
Veterants:
Snake - Konami wants Kojima dead. Not happening.
IC - hardware limitations. 3DS still stands as an obstacle
Squirtle, Ivysaur and Pichu - all three of those were not very popular, and DLC doesn't serve as an excuse to bring back ALL the cut veterans. Same as with Snake, I guarantee you there'll be a lot of non-returning vets. Only reason Roy and Mewtwo got to be DLC is cause they were planned for Brawl but didn't make it due to time constraints. Lucas (and Wolf) fall under the same category in that they were planned development for Smash 4, and then added later on as DLC. Don't delude yourself into believing every character that was cut will come back just cause some vets came back with minor changes.
Young Link - see above, perhaps in Smash 5 if he gets major recognition and is added as a totally new idea rather than a Link clone, but I doubt it. Plus, he essentially transformed into Toon Link. He got mostly decloned, and changed his neutral special. I hardly see the argument in favor of having him aside from a cosmetic preference.
So, what does that leave us with?
Well, on average, these are the top characters in polls for the ballots across western sites, and some of the obstacles that stand in each one's way:
Isaac (Golden Sun) - dead series, and rather medicre RPG if I'm gonna be honest, but he's got a strong backing and if popular demand is met, then he's got a good shot.
Banjo and Kazooie - another dead series, but with a dedicated fanbase and a Nintendo classic. One perfectly fit for Smash, however, owned by a competitor, one who is willing to cooperate however. Overall decent shot, out of all the guest characters, he's the most likely imo.
K. Rool - most likely to become DLC out of the ballots, very popular, and with few obstacles.
Bayonetta - not as unlikely as most make her out to be, but still rather unlikely. Truly, the nudity is hardly an issue and this is evident to anyone who's bothered to play Bayonetta 1 and 2. In all honesty, her biggest obstacle is the fact that Smash 4 is pushing for an E rating, not a T rating like the last games. Under a T for Teen game, she'd have little trouble getting in, and again, those who argue against this, need to play Bayonetta to undertand why the nuances brought up are as irrelevant as they are. Still, I doubt she'd get in, even with high support.
Paper Mario - Decent shot. After Isaac and K.Rool I can see it happening. Again, few bstacles and very popular.
Krystal - with Wolf in the way, I don't think she's got a very good shot. And she's not popular enough in comparison tbh.
Rayman - Not with Banjo destroying polls like he is. Fat chance I say.
Wonder Red - a rather niche character, but probably the best choice after Paper Mario. Still rather unlikely overall I feel though. Simply cause I doubt we'll get enough DLC for him to "make the cut" again, ballot will probably only pull 2-3 characters.
Indie characters:
Shovel Knight - HAHAHAHAHAHAHAHAHAHAHA, game's not even out in Japan, you people are crazy, no amount of support will get him in.
Shantae - if we're gonna be real, this is the only indie character with a decent shot. Overall, I feel that indies aren't gonna get in simply due to the fact that Smash is meant to be a celebration to gaming's All-stars, upstarting indie characters are hardly that, but Shantae has honestly grown enough, and has enough ties to Nintendo to truly stand out above the rest. Overall though... no likely at all.
Those are my closing thoughs. All in all:
Given:
Wolf
Very possible (choose 2-3):
Isaac
K. Rool
Banjo
Paper Mario
Wonder Red
-------------------gap-----------------
Inkling
Elma
Krystal
Bandana Dee
Captain Toad
Rayman
Bayonetta
--------------------------large gap-------------------
everyone else
Unless Sakurai decides to throw some sort of curveball, but with the DLC I doubt it, he seems to be focused on pleasing the fans overall. Plus, it'd be illogical to make a DLC character that nobody wants to get. Probably why they opted for the ballots in the first place.
So, before you start typing up your walls of text as to why I'm wrong in saying that the Pokemon and YL won't come back, stop to think for a moment. "Where do they stand in contrast to the newcomers in terms of popularity?"
If the mons and YL are topping the charts, then you've got a point, however, if they don't, then they won't get any priority over them simply for being vets. Overall, I say expect 3-4 more DLC characters and that's it.
EDIT:
Add the Chorus Kids as a strange ??? somewhere in there as it's really difficult to accurately determine what was indeed true and what wasn't regarding everything surrounding them. It's possible, like with everyone else, but they just aren't all that popular these days aside from diehard bandwagoners. Given that, it's possible they might have just been a scrapped idea overall, much like Dixie Diddie duo, Toon Zelda, and Praimai. Again, if Sakurai throws a curveball in the mix, I'd expect them to be it. That aside, I don't expect them over chart toppers.