Could a demonic plane "break"? It is known that the Subspace Planes could be created, and destroyed, by God. But now that she is gone, they are immutable. The amount is set. Only by losing the key to one can it be "lost". And even then, it has been proven again and again that a living being inside a plane can find a way out, with enough power and time.
But imagine if one was to be destroyed. No matter the power of the occupants, the might and magic they wield... they would be gone, forever. Cast out into the void that exists outside of our reality.
Could a demonic plane "break"? I ponder this question nightly.
-log of current events by Demon Master Dzu