I think it's reasonable to expect that all hardware products conform to the following cycles:
1. The product category is new and super hot. It's also super expensive and hardly any good. Example: digital cameras with floppy drives, computers that can't do much besides text and simple games, cars that barely shifted from horse power to gas. People who can afford it buy that stuff, but upgrade as soon as a new model comes out.
2. The product is decent, but has huge flaws. It is usable for specific tasks, but requires so many workarounds that people can't wait for a new model with a fix. Example: first generations of dSLR cameras, PC computers that are slow but functional, cars that are generally fine but can be safer, more reliable and use less fuel.
3. Mature phase; the product does everything well and users have no reason to upgrade; products are replaced when broken or worn out. The new models always have this or that advantage, which is nice but not enough to warrant an unprovoked change. Example: washing machine, fridge, dishwasher, modern cars, modern PC computers, modern dSLR cameras, a view camera, a pocket calculator etc.
In my opinion, we entered the mature phase of the camera market with Canon 5d. At least that's how it is for me. Since I got it, I never had any wish to upgrade because it does everything I need well enough. I also have a two year old iPhone 4s which works just fine and I'll replace it when it dies of old age, and several core2duo generation computers that work just fine and have no flaws that would require an upgrade.