I'm sure this was decided before the consoles was released. This exclusivity was not decided by console sales it was a deal made by Sony which might be something like they take a smaller cut of the sales which they made it up with people buying the console bundle. Xbox did get the most standalone copy of the game sales for Destiny. I will see if I can find the article about it. Anyways, the main reason for such a long exclusivity is because Activision/Bungie are most likely profiting more from the sales on PS. It really is a bad move on their part as it could cost them Bungie's fans on Xbox and sales on Xbox as some might not want to purchase any more content or future releases from them based because of the long exclusivity. Odds are there is no way for the content to be released earlier on Xbox unless Activision/Bungie pay PS for breaking the contract which will be a couple of million at least but that shouldn't stop anyone from voicing their options about the issue in hopes that this sort of thing doesn't happen again for a multi-console game otherwise other game developers/publishers will start trying to do the same thing.

Lololol someone needs to rethink their statement

You are wrong in every direction.

Someone doesn't understand simple business strategies.