I wouldn't say the Rumors completely dismissed yet.
The poster had some legitimate clout with past leaks and the guess of "wii fit trainer" is just far to accurate for anyone to have guessed while also guessing Villager (some one who Sakurai openly gave reasons for not including last time) and MegaMan being revealed at E3.
Also nothing has been said that has disproved the other 3, we simply did not get them revealed at E3. Pac-Man while rather lack luster with all the possible 3rd party characters imo is highly deserving of a spot and also highly likely despite Sakurai claiming Namco won't get special treatment (he did not straight up say Namco won't get a character) the fact he went on to ask who could represent and discussed Pac-Mans possible moves feels like he's actually just saying "If Pac-Man is in, it isn't because of Namco, it's because he's an extremely well known video game icon".
Mii is something I'd rather not have especially now that we have WFT basically taking the "joke" spot AND representing the newer "interactive" Wii games as a whole (something I feel Mii would also basically represent), but sadly I feel it's also likely simply because Nintendo loves to put Mii's in EVERYTHING.
Little-Mac is my most wanted character and I was extremely disappointed he wasn't in Brawl, that said even if I'm totally unbiased and even if the rumor does prov false, I still feel Little-Mac will get a spot this time around since he has the best case for inclusion of just about any character.
So all that on the table the Rumor had 3 unlikely characters and 3 likely characters.
The unlikely being: WFT, Villager, and Megaman as unlikely (WFT cause... no one was thinking WFT as the joke character, Villager cause Sakurai openly said no for him in Brawl, and MegaMan because at that point a Namco 3rd party was more likely.)
The likely being: Pac-Man, Mii, and Little Mac ( Pac-Man because of Namco, Mii was the likely joke character everyone was guessing, and Little Mac is basically the shoe-in that should have appeared last time in Brawl.)
So having the 3 unlikely's confirmed makes me feel like the 3 likely characters are indeed in, the rest of this rumor was the BELIEVABLE part not the half of the rumor we got confirmed.
be prepared for these characters to be revealed soon.