How long do all of you keep your cameras for before you upgrade/go for the newer model?
I'm running at 5 years per camera at the moment. My wife hates 'gadgets'. Replacing the family camera every 5 years is as often as she will tolerate.
(BTW my wife is a network analysist - programming and managing parts of a large voice/data network, she's not a techno-klutz)
My last upgrade (only a month ago) was to a Oly E510 (from a Minolta D7i) and that was mainly driven by the desire to go back to interchangeable lenses, not 'cause the D7i didn't work any more. It still works fine, after 5 years.
Baring mechanical failure I expect at least 5 years or more out of the e510 body. I expect the lenses to last much longer - but since 4/3rd lenses contain CPU's with firmware and active mechanical things like focus motors, that might be a bit optimistic.
My Cannon T70 and lenses still work perfectly and I bought that lot 2nd hand 15 years ago. Hasn't seen a roll of film for ages, I occasionally put some batteries in and see if the shutter still works. (FD mount, not compatible with Cannon EOS).
There is no reason why a half decent camera should fail after 3 years.
I think many people are just buying upgrades 'cause they can, not 'cause they actually need any particular new feature, and often peer pressure - all my friends have a new camera, i'm feeling left out 'cause I don't' sort of thing.
Of course the camera manufacturers WANT you to keep replacing your camera. They WANT your money. Not value to them if you keep using the same camera for 10 years!