SmashChu
I'm curious to see your stance on today's concept's chances
I assume you're talking about the thrid party and Wolf one correct?
First, let's look at which third party characters got in:
Snake - Requested by Kojima. Confirmed numerous times.
Sonic - Highest requested character for Brawl. Confirmed by Miyamoto
Mega Man - Another popular characters. Fans thought he was going to be in Brawl.
Pac-Man: Mostly because Namco was working on the game, though was only going to get in if Sakurai could use the old design. Somewhat popular, but was very mixed due to his new look and not much in the way of abilities.
Ryu - Never confirmed, but it may have been Capcom asking or Sakurai wanting to add in a fighting game character. Likely done because he's easy to implement (humanoid characters)
Sonic, Megaman and Ryu have some history with Nintendo, as does Pac-Man to a lesser degree. Snake is really a Sony character which is likely why Sakurai didn't ask to have him come back. Also, Megaman, Sonic and Pac-Man (to a lesser degree) were alll highly requested. Let's look who is coming up now
Banjo-Kazzoie - Too many legal issues with the rights to Banjo being owned by Nintendo's rival. Phil Spencer did say he would like it, but I doubt any of the higher ups would go along with it.
Ray-Man - He's dropped off a lot recently and isn't that popular in Japan.
Shovel Knight - Game isn't out in Japan. He's popular amoung message board goers, but likely most people wont know who he is (game has only sold 700K)
Shantae - Everything above, but worse
Bomberman - Konami is in a weird place and may not want to partner with another company. They also want nothing to do with Hudson's IPs so they likely wont give Bomberman
Snake - Sakurai has likely passed on him given his poor relationship to Nintendo. There is also the issue with Kojima and Konami.
I may be missing someone, but you get the point. Sakurai has said that he's not going to add just anyone from another company; however, fans think anyone will be added. If you look at tghe most popular characters worldwide, there will not be a lot of third party characters. Most of the ones I've listed are only really popular in the west. The ones that are popular in Japan are only popular there (i.e. Yo-kai Watch). Snake is the only exception, but Nintendo and Sakurai likely don't want him, and probably wont go though the legal hoops to get a veteran.
The most popular characters right now (as far as we know) are Wolf, King K Rool, the Inklings Bandana Dee to a smaller degree. That's not to say these guys will get in, but if you are talking popularity, you'd look at these guys.
So I would say the chances of a new third party character is slim since there really aren't any other strong characters left. As for Wolf, he's likely, but I would not say 100%. You never know what Sakurai is going to do.