The guns should not be left behind, but new ones should have exclusive and better perks in their perk pool which older guns can't roll with. Those perks can be better than the ones we have atm. That way you don't have to nerf anything nor take away our favorites. You want us to play new stuff, alright, this is the way I would use new stuff... And I am nit one running meta guns in the endgame. I always go my own way. That's why I dislike the retirement idea overall.