I have no idea how how we got on to the topic of how books factor into an undead uprising, but Stacey from Page Turners Blog and I got to discussing it after I went to the bookstore last night. My thought was that everyone should buy one physical book for every so many (you can set the number) e-books they buy. That way there will be plenty of books still hanging about even if you aren't. (Sorry to be realistic, but it is the zombie apocalypse and if you've been bitten we aren't going to be all mushy about it.)
You see it in zombie movies and shows all the time. The encroaching hoards take a brief hiatus, and one of the characters finds an old paperback somewhere then kicks up to read. It's never the best book, but it's something.
The trouble is the advent and rapid adoption of e-reader and e-book technologies makes this nearly impossible. Barring the use of a generator, the power will eventually go off. And even if you have a generator, gas is a precious commodity and it will soon be available in increasingly limited supply.
I am by no means saying that you should boycott e-readers, but think about the future! Keep buying hard copies every so often if you want books to survive the zombie apocalypse because unless you own a huge solar array or a hamster farm them your e-reader just isn't going to make it. Sorry to be the bearer of bad news.