I honestly don't think we're getting Sora because Sora is a huge character that would've been revealed at E3. Same deal as Minecraft Steve. Those characters are meant to attract other audiences, not please the Smash fanbase, and as such you'd want them at E3. The fact Ridley was chosen for E3 seems to imply, to me, that Ridley was the biggest thing they had to offer to its fanbase, and all the other characters revealed so far imply that is the direction the game is taking.
Is Vergeben right about what he says? Honestly, who cares, especially concerning Isaac. He didn't know about K.Rool, which shows his information is incomplete. Will there be a Square Enix character? If there is one, it would have to be Geno. I don't like Geno at all, mind you, but he's one of the big Smash requests and the sole Square Enix that wouldn't be a gaming megaton, thus the only Square Enix character that would make sense outside of E3. Minecraft content? Sure, a stage or an Assist Trophy would be nice, but if there were talks to get Minecraft stuff in the game, it's probably because there were talks about Banjo. There's no doubt that a Minecraft character would be seen as a bigger deal by the gaming community than just about anything else, and that's why it would have been announced at E3. Incineroar is the Pokémon newcomer we always get, and Ken is the first echo fighter, which makes sense in this game especially considering Capcom seems really generous with its licenses.
What I mean by that, it's that all of Vergeben's leaks make sense, has a good track record, and they are probably true. But everything we've seen so far screams "this is the game the fans want", and it'd be weird to suddenly throw it away because "Sora is more popular than Geno", "Minecraft sold more than Banjo Kazooie", or "who gives a crap about Golden Sun". If those things were true, then why would Sakurai choose to reveal Ridley of all characters at E3.