I've had my Sony PRS-505 for more than two years now - still runs like almost new (the battery has a bit less life than before, but I still get roughly 3 weeks per charge with heavy usage).
It's been dropped on concrete with only minor damage. I have various cases, but have never used a screen protector on it. I even read in the bathtub with a M-edge Leisure case.
There are people here who are still using a Kindle 1. I think some even still have PRS-500s and even a few eBookwises.
In other words, an ebook reader should last far longer than yours did.