The trouble is, most of this guy's "info" could be written by any well-informed, up-to-date Nintendo fan. It's just vague enough that almost any of us could write it up and have most of it seem convincing.
Obviously, the info about Mario and Zelda in particular is just common sense. "Big, grand adventure. Makes use of GamePad. Been in development since finishing the last 3D Mario." I mean, duh. Obviously. If the new game didn't meet any of those requirements it would be unusual.
Zelda... 2015. Yes, probably. Since Iwata and Aonuma were concerned enough about the wait that they decided to tide people over with a full Wind Waker HD remake. It stands to reason, it probably is a 2015 title. Supposed to the "grandest in the series", "may or may not be in the E3 Direct." Come on. This is all info we pretty much already know, as people who have been with Nintendo for a long time and have come to understand how they operate the production of their top franchises.
The Screamapillar is easily identified by its constant screaming—it even screams in its sleep. The Screamapillar is the favorite food of everything, is sexually attracted to fire, and needs constant reassurance or it will die.
