If you shoot that much, a new barrel is alot cheaper than the ammunition you will put through it. Don' t think of a shot out barrel as an ending, but think of it as an opportunity- an opportunity to install a premium aftermarket barrel.[8D]

Almost all of the wear on the barrel will be throat erosion- unless you are careless with cleaning, which can ruin a barrel much quicker than shooting it will ever do.
To compensate for throat erosion, you may have to clean the barrel more often to get the fouling out of the throat area, and seat the bullets slightly farther out to compensate for the change in the length of the throat.