Coexisting dimension when one of them is destroyed

I’m starting a homebrew DnD game set in the astral plane, and the inciting incident of the campaign is the complete destruction of the Prime Material plane. In standard DnD cosmology, the prime material plane coexists with the Feywild and the Shadowfel, planes of nature/fairies and spookiness, respectively.

So…what happens to these places when the world is blown to smithereens?