I wrote out a concept for the creation of several item tiers above ancient, covering all items types: Weapons, Armor, Jewelry.
The tiers are Primal, Ethereal, Epic and Mythic.
We need several loot tiers to vary the builds and make the item hunt more interesting. Finding item(s) in a certain loot tier can possibly enable build traits otherwise impossible to glean with ancients: CDR for fulltime buffs, new AS breakpoints, or passive heavy builds that are potent or hold an edge from extra utility.
The aim is to prolong the loot hunt and specialize without completely undoing the baseline of what the current ancient item tier offers.