Let's not worry about whether digital comics will destroy print copies ("floppies" heh), and instead focus on the balance that is struck between the two formats. Digital comics can lead to readers seeking out "floppies," and vice versa.
It's a beautiful thing. Author/illustrator Dan Hipp is showing just how this is done, by posting the entirety of his first two volumes of "Gyakushu!" online to entice readers. The third volume is finished but has yet to be published due to Tokyopop being in upheaval ownership-wise.
Do yourself a favor, hop over to Hipp's blog to read "Gyakushu!" and get hooked on a new book.