It doesn't even make sense: one of Bungie's arguments for sunsetting is 'power creep', the bogeyman of game design where every new content release with new loot has to be 'better' (i.e. do more damage/have faster TTK) than the previous, eventually results in old PvE activities becoming so easy to complete because the newest gear lets you one-shot the boss. The fact that Bungie are even worried about old PvE content makes me worried that they have no compelling new content, because otherwise why would worrying about power creep even matter if there's new, better, more fun PvE content that people will be playing (which is how it works on MMOs). But the fact that Bungie are actually stating that they want to add new, more powerful loot into the game... is literally power creep, so if it really is better, more powerful loot, there would be no need to sunset old gear and guns anyway since people will gravitate to the new, bigger, better guns and armor. And it'll throw game balance right out the window, as per usual with Bungie's insistence on constantly dropping new OP loot into the game.