In J.K. Rowling's case, in many times it WOULD be a lost sale, because Potter nuts have already shown they are willing to buy her books over again in different formats. Many Potterheads I know have the books in hardback, paperback, British "adult" editions, audiobooks, etc. (I have them all in U.S. hardback--the first three replacements for previously purchased paperback editions.)
I would welcome the opportunity to purchase legal versions of her ebooks, if they were properly formatted, because there are places in the books where handwriting fonts, etc. are used and would probably have to be rendered by images. I would also love the inclusion of the wonderful Mary Grand Pré line drawings at the beginning of each chapter in the U.S. versions. I would still keep all my paper editions if I purchased ebook editions. A friend sent me bootleg ebooks of all the novels and they are OCRed and not proofread and generally a mess. I've never bothered to read them through.
Also, my understanding is that JKR doesn't prevent the release of electronic versions not so much because she fears piracy as because she just doesn't like ebooks. I read somewhere that she said she doesn't want to deny someone the opportunity to read the paper version of the book. My answer to that argument is: she isn't. She's just giving them a choice.
