You, sir, are a genius! And you have caused my brain to function at more than idling capacity (which doesn't happen often in this country). I salute you!
Of course, in my own D&D cosmology, it's actually the plane of Shadow in which all cosmologies coexist like apples in a barrel (or in my own words, like islands upon an infinite sea). But your post is something I can take with only slight alteration and actually present to the PCs as text right out of a book their PCs find fragments of. This is great!