Well, the only time I bought hard cover books was at the Dollar Tree or from the markdown area.
So no lost sale from me. I did subscribe to the Reader's Digest Condensed books which are hard cover. Got about a dozen (each one has several stories). Don't think I finished reading them. I even bought paperback books on clearance or from the thrift store. So the publishers are getting more money from me now.
I don't care to read hard cover books. I can't fold them back and get comfortable!
But, I don't think the Publishers can blame eBook readers for the drop in sales entirely. In this economy who wants to pay $20 and up for a book! I can get several books for that price.