Bungie should just add a new difficulty to the current raids whenever the level cap is increased. The new difficulty would essentially be as difficult as hard-mode on the Crota raid right now, for instance. The raid mechanics would just stay the same as the hard mode, but with higher level enemies and bosses. The hardest mode of the raid should drop GUNS, not armor, of the highest current damage available, as well as energy to upgrade them. The effect this would have is that everyone still plays the latest raid (Crota) to hit the current level cap (32), and after hitting that cap, they are equipped to attempt the new difficulties on the previous raids (VoG) and get maximum damage weapons. Or, you could just send me a new Fatebringer to the special deliveries NPC (which be much easier to implement).