You know, we could argue which world was 'on top' but I have a feeling that Ryukishi could very well write that both the Meta-World and Rokkenjima-Prime cross-created each other. And that in each world the other would be viewed as subordinate.
For his next series, if he continues to develop Bernkastel and Lambdadelta (or anyone or anything from the MetaWorld) further, he may need to justify their existence if there was some doubt previously
I imagine he would butcher another quantum theory about dual particles (i.e. proton and anti-proton) coming into existence at the same time and travelling away from each other with exact, but opposite spins, and yet always tied to each other via Quantum Entanglement.
