A twelve hundred pound animal with four steel shoes can do a pretty good job of grinding down most surfaces, and consider commercial facilities with a number of horses pounding the surface. If the base was built well and the arena has been well maintained, only the surface material will need to be replaced. Good maintenance, including frequent dragging, can extend the life span of your arena greatly. If a track is allowed to form that wears into your base, you may be in for big trouble. Of course, the frequency of dragging depends on the footing and the amount of use the arena gets, but consider dragging as soon as the surface seems to be different depths, before you can actually see a tract forming.
Some busy barns drag their arenas three times a day.
A word of caution about dust control. While more and more products are becoming available to cope with this problem, some of them can actually make your surface material compact and lose its spring sooner. The best product for controlling dust is still water. Riding surfaces come in many types , sizes and price ranges. With the many choices available these days, consider taking the time to plan ahead and do it right from the ground up.