New way of getting bounty mats: 1 add in a new Key Warden for act 5 and then with the infernal machine keys when you use them for each act will only have the Uber bosses from that act only and have 3 per act exp (act 1 The Butcher, Queen Araneae and The Skeleton King) and so on for the rest of the acts.
When you have killed them they would then drop DB’s, Gems and some bounty mats for that act. This way you introduce a new way of getting bounty mats, but it wouldn’t effect running bounties since there is gear that only drop from the Horadric Chests for those acts.