Extremely accurate, highly durable shutter unit proven by 150,000 cycles of shutter-release testing
The D7000 has a shutter speed range of 1/8,000 to 30 s, with a top flash synchronization speed of 1/250 s. The newly developed shutter unit, that has an equivalent performance to that of the D300S, is tested for 150,000 cycles with the shutter actually loaded to prove its high durability. Furthermore, it employs a self-diagnostic system to ensure precise exposure. This system accurately monitors how long the shutter curtain is open, and if a variance between the designated shutter speed and the actual shutter timing is detected, the camera will automatically maintain shutter speed precision by gradually shifting the timing of the rear curtain movement. If a large variance is detected, the monitor recognizes this as shutter failure and flashes an error message in the viewfinder.
you can use your camera till its shutter fail. you never know when it will fail, you will only know when it fail. The figures provided is a rough figure. it can fail before or can last way past the estimate. there is no need to worry about shutter failure. Most probably, you will upgrade before the shutter fail.
Should the shutter fail, you can get it replace at the service centre. with a cost of cost.
i guess when the shutter fails, it does exactly as what it means.. it fails..
i personally think that one shouldn't be too worried about the shutter failing and too conscious of shutter counts as it defeats the purpose of photography. just be trigger happy, and pay a small fraction of the cost of the camera to get the shutter replaced when the time really comes.