Likelihood: 61% - If we get another Mario rep, it'll be Junior. There, I said it. He's the most prominent/important Mario character left over, and while he has competition in characters like Toad, Paper Mario and Waluigi, all of them have some decently sized roadblocks standing in their way of playability. Toad has his inherent generic nature and his position in someone else's moveset, Paper Mario has the stigma of being a second Mario (even if he definitely has the potential for uniqueness), and Waluigi has both the Mario rep/Wario rep confusion going on in addition to his apparent inability to appear in a non-spinoff title.
With all of this in mind, and given Nintendo's love for the character, seeing as how he's included in basically every mainstream Mario game since his inception, I feel like Junior's biggest challenge is going to be whether or not Sakurai decides to add another Mario slot or not, which I feel is a bit better than a 50/50 chance, especially if potential DLC is taken into account. If he's not in the main roster and Sakurai does DLC, I'd bet money on Junior being in one of, if not the first DLC package.
Want: 65% - Junior's never really been something I've specifically wanted, more of something I've just expected. However, he's much more intriguing than his competition to me with possible paintbrush antics, and the potential for a Shadow Mario transformation has always been something I've hoped for if he does end up making the cut. So he earns a higher than 50/50 percent want for me because of that.
Nominations:
Samurai Goroh x3
Medusa x2