Brakes in electric cars receive vastly less wear than conventional vehicles, feels like literally an order of magnitude. They really only come into play at all during final stopping and emergency braking. The separate parking brake design on the Tesla is an interesting related detail.
In my experience so far (Prius, 110000 miles) it is more like 5x. And the Prius brakes are tiny things, especailly compared to the huge brakes on the German cars I've owned in the past. The Tesla S is comparable to them in weight and handling, and the brake system looks comparable too. From the testing and reviews we know it has excellent stopping distance, so it looks to me like the best of both worlds. I wouldn't be surprised if it gets 10x the lifetime out of brake pads, depending on driving conditions of course.
