My opinion on leaks: Wait and see.
Eventually, there will definitely be a leak somewhere along the line (even Sakurai can probably admit this), and eventually, those of us devout to finding the true one will find it.
I not sure.
But I mean, we're talking about Namco here, if I'm correct, isn't part of the development team from Tekken helping as well? I think we're in good hands.
Street Fighter is my favorite "traditional" fighting game, but Tekken I think is hands down the best fighting game franchise of all-time. The reason I don't personally enjoy it is it takes too much to get into, because each character IMO actually has too many choices with moves and playstyle.
Soul Calibur... I'm not big on combos, but I love the presentation. They do have that noticeable Sakurai random newcomer element, with guests like Link, Spawn, the 3 Star Wars characters, Kratos, and Ezio.
What I'm getting at is that I think Namco Bandai (both the Tekken and Soul Calibur crews) were the ones behind most of the Rosalina ideas (the Tekken crew liked all the different moves of the two, the Soul Calibur crew liked the concept), Sakurai was in the same role for the Wii Fit Trainer, and the Soul Calibur crew at Namco Bandai was the most "behind" the push for the Villager, although I imagine Sakurai was definitely heavily involved there. Mega Man... was obviously a choice everyone had to be behind, especially since Mega Man (along with Miis and Pac-Man) is the last real "superstar" left that could be playable in Smash without breaking Sakurai's "rules".
So this begs the question, "what characters do we think the Tekken and especially the Soul Calibur crew will push for next?" We gotta think crazy like them. And for some reason, I keep coming back to a tag team idea (people keep saying Diddy/Dixie, but I keep thinking Plusle and Minun and the Baby Mario Bros.), a giant super huge character (these are in Soul Calibur a lot, and a good example is Nightmare; I am thinking of K. Rool), and someone with huge range, probably with a weapon like a sword or a staff (Isaac, Shulk, Lyn, and especially Takamaru come to mind).
As for the Tekken crew, I imagine they helped spoof of Bowser, Samus, and Link to where they are now, and I imagine they also helped spoof up Ganondorf, Lucario, and maybe even Mewtwo. I also imagine they'd push for a character that uses various martial arts-esk moves probably based around said martial arts (or even pro wrestling), so Little Mac may be their personal experiment (as well as the Wii Fit Trainer a bit, since she seems somewhat like that), or even say Takamaru, Pac-Man, or heck, K. Rool.
I imagine Sakurai would be drawn to crazy out there concepts. I think Ridley, Pac-Man, and Miis might be his personal forte of potential newcomers.
This is an area where I feel us thinking like roster speculators and leak truth finders is one in the same.