I valued my time on the old content up until it became obvious that my time was rendered pointless. You literally had no reason to play the raids or strikes multiple times outside of hopefully getting those various Legendary/Exotic weapons and armor that you were looking to get. My point is that if everyone had already owned all of that stuff, then no one would have been playing Destiny because the game lacked actual content with a solid enough foundation for its PvE side. It didn't hold up on its own without making itself into a total grind to keep the player engaged in it. I don't see any reason why the old stuff couldn't go hand in hand with the new. They could very easily design a new tier for Prison of Elders where players need to go and complete it for a new challenge that enables them to convert existing weapons and armor to whatever new system is being used in TTK. It wouldn't be all that hard to do.