about 1100 rounds of top accuracy and then it starts to fall off. This is of course with relatively good barrel care. Shooting lots of fast strings and overheating your barrel will cause it to go faster.
The majority of the wear is that the throat area. Some people cut down their barrel 1 inch and re chamber it every 800 rounds or so. I guess the rifling is the last part to go on the barrel.
This info was found at 6.5-284 Cartridge Guide
This website has a lot more information on the 6.5x284 and will answer all your questions.