A Zereth Mortis like system that covers all 10.0 zones, then when doing world content you can find and open 'timerifts' which teleport you to a solo version of any preexisting WoW dungeon. To fight through it getting anima-like powers on the way.
It rewards a piece of gear which has WQ ilvl, but also has a diablo-like legendary power that only works in outdoors and these solo 'timerifts'. Plus some materials for complexity progression akin to m+.
When a patch drops you can disenchant new gear to update the ilvl of old one to relevant WQ gear ilvl so you don't have to go not same legendary power again. But patch should add a bunch of new powers to acquire.