I think they will soon learn that readers will pay what they need to pay to read them and prices will steadily go up and settle at $12.99 to $14.99 for most popular best-sellers.
Maybe. On the other hand, readers may decide they don't want to pay $15 to $20 for an ebook, and find authors at the $5 price point.
That's true for me... I have authors I love, but no way will I pay $20 for their latest bestseller in ebook format. Nor will I buy the paperback. I'll look for new authors, and I've found several where I've purchased their entire backlist -- at $4.99 each.
I'd rather have four books to read at $5 each, than one $20 bestseller I may or may not enjoy.
Ebooks change the publishing game.
Good news for new authors, a wake up call for publishers.