The Sorting Hat kept up with the trends! It knew that the world was scheduled to end on May 21, and all the righteous would be uplifted to Heaven.
Since the Sorting Hat knew itself to be the wisest and most righteous being of all, it came to the most logical conclusion.
Upon waking from a nap on the afternoon of the 21st, and realizing it was still at Hogwarts, the Hat understood that it was already in Heaven.
Hogwarts was heaven.
"Halos and harps for everyone!" the Hat decreed.
And so it was. House elves brought everyone gilt halos and strap-on wings and hand-held harps, or autoharps, or the occasional harmonica (the house elves had taken to tasing one another for fun, and their mental acuity was not what it once was). The Great Hall (still home to the wax display of Hatsguard Heroes, mind you) was bedecked in white draperies, tinsel, and leftover battle fog from the Harkonnen Dining Experience machines (the Hat felt this would create a cloudlike effect). Angel food cake and ambrosia were the evening meal. Oh, and cans of Red Bull ((at player suggestion, because it GIVES YOU WINGS)).
Debbie Gibson's BELINDA CARLISLE's "Heaven Is a Place on Earth" was piped through WART, the insipid soundtrack of Hat Heaven. Alternating with the
Elvenking cover of same ((thanks to Igor-mun)).