I'd like to see e-paper used in places other than ebooks. Static, powerless displays could be really useful in so many areas: cell phone/computer notifications, wall calendars, daily reminders, or anything that changes less than 30 times a second.
E-books are perceived to be a large untapped market and every other display tech is basically a heaping helping of fail, so it is no wonder that this use case is in the driver's seat at the moment. OTOH, I think you are correct that in the long term we will probably see e-paper replacing a lot of displays that are currently poorly served by LED/LCD solutions. Batteries that can tell you the charge level before you stick them into something was one of the better examples of this I heard recently.
The E-Ink guys had a decent business in train station information displays. They would replace the old 'flip' and led style displays with cooler running e-ink.
