The myriad of churning Artonach hatching posts, Telvanni pocket dimensions, Imperial Battlespires, Sotha Sil experiments, rogue Magna Ge varliance and other stray creatia that coelesce into the hamlets of the void, existing for moments or millenia depending on numerous factors, swirling about with no certain masters only petty kings, arch-lich's, elemental daedra or forgotten spirits who inhabit them for a time.
That sounds like one heck of a party.
Would any of those make a large enough dent that they would be counted as unique realms?