Here's why it won't happen with Destiny: (Gaming)

by dogcow , Hiding from Bob, in the vent core., Monday, March 14, 2016, 17:53 (3176 days ago) @ Blackt1g3r

I would think as long as the games are using the same networking code (and assets of course) it wouldn't really matter what system the game is running on. The harder part for Destiny is the exclusives. Either they need to make you able to transfer your character with the exclusives intact (which might be against the contract for the exclusives), or they need to have some way of requiring your character to remove their exclusives before they can go onto the other platform.

Simply dealt with. PS4 characters are only playable on a PS, Xbox characters are only playable on an Xbox. However those characters can cross play with the other consoles. Xbox peeps could see me use my hawkmoon (I don't even know what this year's PS exclusives are) and die to my hawkmoon, but I couldn't play with my hawkmoon on an xbox as it's tied to my PS character(s).