The $100 you're shelling out every year for the new edition?
Have no fear, the Kindle supports this cherished feature of the paper-book experience.
(Seriously. Publisher removes old book from central location, publisher uploads new book. What are you going to do, buy copies of the old one used from the non-Amazon place you can load your Kindle from?)
It is generally acknowledged that e-readers aren't yet as good for technical books where you will flip around somewhat randomly, and want high quality photos, etc. We need somewhat higher resolution, color, and a nice interface for flitting around from place to place.
Novels, on the other hand, are read pretty much linearly, and are great on an e-reader. (Honestly, I've always hated fighting with bindings on physical books.)
On the other other hand, perhaps at lower levels forcing students to read for information might have positive side-effects. Ctrl-Fing and quick search functions do make the Internet a different experience from the textbook, after all.
The $100 you're shelling out every year for the new edition?