I see this as a great opportunity for both readers AND writers alike. As a reader, I'm constantly purchasing the kindle versions as I have ZERO patience. Even with second day service through Amazon Prime, if I get excited about reading something, I want it now. But I also have a very large collection on my bookshelf, and I like to add anything that I'm pretty sure I'll read again. And if it's something I end up absolutely loving, I HAVE to have a copy so I can put it up on the shelf, and fawn over it daily. But the times I do buy just the hard copy of something, every time I wish I had the digital copy, too, so I can read it in the dark when my husband is snoring at my side, or when we're on a trip and, of course, I've forgotten the book at home.
Although my digital books are already sold at a low price, and therefore I likely won't participate in this program, big time authors who sometimes charge up to $9 for a digital copy will probably make a little extra money on those of us who want both versions, but can't necessarily afford to buy both at full price. It will be interesting to see what big-named authors choose to jump on this bandwagon. It's just as they say, the publishing industry is changing. With mega companies like Amazon leading the way, you just never know what new idea will influence the way we read next.