The world would fall.
A new ruler over Middle-earth I would imagine!
would make a very interesting fan fic
Someone came up with a theory that Tom Bombadil could actually be evil:
Best thing I've read all day:
And one dark night the old trees will march westward into the Shire to feed their ancient hatred. And Bombadil will dance down amongst them, clad in his true shape at last, singing his incomprehensible rhymes as the trees mutter their curses and the black and terrible Barrow-Wights dance and gibber around him.
And he will be smiling.