Lower, Middle and Upper Realm, that is what form the universe that all the cultivators live in and to Qi Condensation to the Dao Ancestor stage it his the path to immortality that all those cultivators strive for.
But what is beyond, outside of this universe that all those cultivators live in? A Primordial Chaos Dao Ancestor.
A Primordial Chaos Dao Ancestor is not really the next stage after becoming a Dao Ancestor by the fact that the universe that the cultivators live in can only make cultivators able to reach the Dao Ancestor stage, it is a stage where a Dao Ancestor manage through heaven-defying method to absorb different law of heaven and earth in his own being making him able to open the sky and reach greater height by cultivating the law of chaos. (it is know that to cultivate above Grand Ascension, a cultivator cultivate the opening of immortal apertures but most importantly the law of heaven and earth that they have to choose one of many).
But it come at a cost, in contrary to a being like Pangu who opened the sky and sacrified his own being to make the world, one has to open the sky and swallow the world (tantamount to destroying it) to become a Primordial Chaos Dao Ancestor, making one that try to reach this stage the enemy of all living being in all of the existing realms in the Universe.