I love ARPG Games Diablo 2, Path of Exile and so on, they have a unique mode that challenges the players that find normal mode easy.
A Hardcore mode, when you die you lose everything, and have to start over.
Now imagine this mode being in the game after you completed NG or NG+ and so on.
After your character dies, he becomes hollow, a part of this world a black phantom, and when your new character will enter the same place where your previous character died, that previous character invades as BP, drops souls humanity etc, and random piece of equipment.
A hardcore mode, would be just as normal mode (which should be hard, even harder than Dark Souls, or even Demon Souls) just for more replay-ability and for hardcore players, PvP doesn't count as hardcore death, or should it?