Bungie would have been better off making weapons fall into four categories plus exotics. Grey weapons have 1 mod slot, green have 2, blue have 3 and legendary have 4. You have all the weapon types still but all perks become mods that either drop in world, can be bought from Banshee with mod components or require certain triumphs or in-game activities to obtain. You then have to 'unlock' the mod slots on a weapon using upgrade currency. Each slot being more costly in currencies than the last (a bit like armor is now). Weapon 'rarity' (color) dictates how often they drop in world or again, you could 'craft' them using currencies. I think the armor system works just fine as is. Just drop sunsetting on it. If this happened, there would be no need to sunset things. Once a mod is slotted into a frame, you cannot remove it and thus if you want a different combo you have to build another frame. This would also allow them to introduce new, desirable perks and frames and players might just enjoy grinding out what they want. You could even have the champion mods be available this way, one mod for each champion type that can be slotted in any weapon but only one champion mod per weapon. In fact, you could make this super simple. 1. Make all perks mods. 2. Give all mods a cost like armor mods 3. Give weapons 10 upgrade points like armor has to govern how many slot points you have and when masterworking occurs. 4. Have frames drop as outlined above (masterwork type is a mod as well, energy type is random and can be changed just like armor) 5. Provide methods for farming/obtaining mods. 6. Player slots a mod permanently into their weapon frame.