As a college student, I see a few problems with switching purely to electronic textbooks. 1) I would have to verify in every class that it's okay to be using a laptop or tablet - that's been the case in most of the classes I've had, so it's unlikely to be a huge problem, but still. 2) It is extremely unlikely that a laptop or tablet would be permitted in open-book tests (which, while uncommon, do occasionally show up, and are invariably more difficult than close-book tests). I would have to rent a textbook during the test, or arrange to borrow one from another student taking the same class at a different time. 3) Physical textbooks are really, really good at random-access. This has often been very useful when looking for constants without losing track of the pages equations are on. While electronic textbooks do let you skip randomly between pages, it would end up being a mixture of memorizing page numbers and looking at the table of contents.

EDIT: removed issue four, because I completely missed that this is an addition to the current kindle system. (Text was "4) Renting. There doesn't seem to be an option to buy the electronic copy and have it forever. I might be unusual in that I'm keeping several of my textbooks that are either directly related to my major or very good, but still.")

On the other hand, there are some classes where I've hardly used the required textbooks, or where I know I'm not going to need to review them, so electronic textbooks could be useful for those. The problem is knowing in advance which classes are which.

(I just checked how much my textbooks for the next semester will cost. Around $700, used. Ouch.)