Yeah - the main things you have to worry about rim wear - and like Zen said, some have indicator dots and the hub, but if you do regular hub service (repack bearings) then your hubs should have a long life. 7,000 miles, 700 miles, its going to depend on the conditions. If you ride in wet, gritty conditions a lot and are braking often you'll wear the rims pretty quick. If you always ride in nice weather and do long country rides without a lot of stop and go, who knows how long they will last.