The only thing that would justify the secrets and delaying, and the name being hidden. Is if this Zelda game involves jumping between the games. Example: One dungeon requires you to go to OOT world and deal with a boss. That has entered it. ALA Back To The Future Part II time changes.
That is really the only thing I could think of, that hasn't been done in a Zelda. Why the game is taking so long. And the title being not revealed. I'm probably nowhere near right. And it will probably end up being some generic reason of the usual Nintendo polish.