We have Bosses here that we go to farm duriel andarniel ice beast varshan glacial fissure. Have you thought about the fact that they would drop unique parts of the key with each boss? Which would we connect with craft mechanics and somewhere on the map would there be a entry or a tunnel with Hell’s Gate? There would be massively heavy hordes of demons of all types that we would have to cut through to get to the Boss, for example, like the three-headed dog. And would he give us new improved items, for example, a heroic item and a higher power item? And with the fact that after killing, we would continue on the same path to another boss, for example mathael, and so on, it would just take us to hell as it is written in the lore? for example, it should be leveled Inferno, which would scale character stats so that we and scale dmg, and the bosses would not be for one shot, but they would have a fix like worldboss, so that the fight would be literally interesting? in lore,
there is a lot bosses that you can draw from, I think it would be an interesting endgame mechanic, every game has its pluses and minuses, and development also costs something, I’m not going to criticize anything, but the endgame content is lacking, so I got this idea 
I just want to help in endgame mechanics
The second part, when we already have heltide, why don’t we have for example cursed areas like vampire curses on regions or hell where we would also get things like in heltide, there would be other drops, not cinder, but blood curses for which we would they chose equipment or rewards of various types, whether material like resplendent spark or other useful things