It's one of the reasons, trying very hard to keep my biases aside, why I'm certain there's probably Minecraft content, much more unlikely for there to be a character--or if there is one, perhaps it makes sense as DLC. It's only recently that we've heard from the shaky leaker that he thinks a character is in, but we don't know when Verge's non-main sources heard murmers of there being a *character*. We also don't know the trustworthiness of these sources, or if they're the same, given we don't know how Hitagi corroborates his sources, unlike Verge.
And it makes sense that nothing was said at Minecon, even if Minecraft content is in Smash, because Nintendo tries very hard to control information. EVO wasn't different--it's why they merely announced a Direct, rather than show it at EVO, it was the equivalent to a Twitter announcement. Whereas in neither EVO nor Minecon can they guarantee Nintendo and Smash fans would be watching--it's why information about their games only come from official Nintendo sources. Ubisoft could be considered an outlier, except Star Link isn't Nintendo's game--it's an Ubisoft game with Nintendo content in it. And, in fact, I saw many Nintendo fans confused when watching Nintendo Directs, not knowing what Star Link was or its connection with Star Fox. That's the exact situation Nintendo wants to avoid with their own games.
And so just like an Ubisoft game with Nintendo content makes sense to be shown off by Ubisoft--if there's Microsoft content in a Nintendo game, like Smash, we can assume we'll see it in an official Nintendo presentation. Though, out of fairness, if we want to talk about Banjo in the lead up to the XO18 conference in November, I'm not gonna complain.