"This story isn't a mystery" -- Tony Daniel
It sure isn't. Just a couple of comments break it down very efficiently. In a March interview, Grant Morrison said that the Batman he'll be writing after BFTC will be a "light-hearted and spontaneous Batman" with a "scowling, badass Robin"
Now, go back one year. Morrison spoke about how different characters would be if they were Batman.
Tim: "grim and determined." Is that "light-hearted and spontaneous"? No.
Dick: "kind of a circus Batman. He’d smile a lot more. He’d be really fun.” Is that "light-hearted and spontaneous"? Yes.
Damian: "he’d be the hard-ass Batman. He’d happily pull your head off, if need be." Is "hard-ass" about the same as "badass"? Yes.
Done deal. Dick will be Batman and Damian will be Robin. For all of the hoopla over Tony Daniel having given it away (he didn't), it was already laid out directly by Grant Morrison.