This is because "You Da One" only reached #26 here in Australia. Same thing happened when "Hard" didn't do well. We were the first to move right on to "Rude Boy" and it went #1.
Obviously kanye's verson is to sell more copies cause fans who already have the album would still buy the single cause its new. I think kanye would sound great on it
They may be doing it because of Jay's baby. He probably wouldn't have time to film the video/promote with a new born, so maybe they are swapping him for Kanye...