good question My Carquest is a rather secluded location and doesn't appear to get much business. The store itself looks outdated inside and out.
As you mentioned, the inventory also looks like it has been sitting a while. My guess would be that since it in a climate controlled environment that it should probably last 2-4 years. Nothing that a good shaking wouldn't fix.
Here in Jacksonville, Fl we just got a brand new carquest in a busier part of town. I've been meaning to stop by and check it out because the other one even has some good 3M products in the auto body/paint section.