According to a paper that clarivoyants say physicist Stephen Hawking will publish at some point after This Novel Slew Empires' release, the novel's theme is "everything, ever. And I mean ever."
Attempts to narrow down the theme will fail.
Though the novel's ambition will be lauded, some crackpot conspiracy theorists will denounce it as "the product of the bullwhipped and sad mind of an actual novelist feeling bad about his struggles to complete a draft of his own, actual, very shitty novel which is also too ambitious for anyone's good." This theory will be discredited immediately by someone smart.