Yeah, but book sales as an industry seem pretty stable. And a long successful author (the Grisham's, King's etc. as well as some less extreme examples) know everything they put out will sell millions of copies.
In the past the price per copy was stable, only going up slowly with inflation as cover prices rise. They shouldn't expect the price per copy to drop just because people think the cover price for e-books should be significantly less than the print version. Income per copy sold shouldn't drop--income per book will of course be variable as number of sales will vary.
Barring the DRM issues of course, which do put less value on the material as it restricts usage. But even in a DRM free world, people would still bitch that e-books should be cheaper due to not having printing and material costs, shipping costs etc. But that doesn't change the fact the author's work didn't change and that they should get paid the same per copy as they do for print copies sold--now that's not all on the consumer, publishers should just take less and give more to the author for e-book sales where they don't have those costs. So maybe prices can be a bit cheaper for e-books, just not drastically so and at a level that Stephen King gets $X for each hardcover of Under the Dome and $X for each e-book--and when the paperback is out he gets $Y for each paperback sold and $Y for each e-book sold after the paperback is out.
In any case, that is my take on it. And we're starting to go in circles, so I won't bother repeating that take over and over anymore.