As Publishers Weekly puts it, in June ebooks jumped while print plunged:
$48.4MM trade paperback
$47.4MM mass-market paperback
Adult paperbacks were down 64% in that month.
Well before the last press has punched out its last paper book, we will have switched to thinking that p-books are print-outs of e-books. That’s when the switch will have been made, just as occurred when we switched from typewriters to word processors. That Day of the Modifier — when physical books need a modifier to specify them — is coming fast.