Confirmation of what many fans believed to be the truth all along.
One step closer to Grey.
Once again, reverse engineering of Pokemon games has put us one step closer to the ultimate question, the answer to which is 42.
edit: should probably add this:
Usually Nintendo's trend is to reveal alternate forms of Pokemon later on in the generations. (Well, at least that's what they did in Generation Four.) And although they delayed the forms for later in Generation Four - and thus left an excuse for the placeholder data, that doesn't explain why they did it for Generation Five.
It's tradition they would reveal the new form of Kyurem, if any, later. So why did they leave the data in? I suppose we may never know.