At what mileage should I expect my brakes to be replaced

I have 46,000 miles....and rarely city drive....

It is a big car and heavier than most but........anything more than front pads and rotors would be a complete shock. Rear drums and shoes will last 2 to 3 times as long as the front brakes. I wouldn't pay from more than front pads and rotors if I was in your shoes. Forget the dealership. Take to a local shop and have a free inspection done and get their opinion. Probably, just front pads need replaced. Get the lifetime warranty front pads and all brake pads will be free as long as you own this car.

Thank you so much for your advice, it was very helpful....I will do exactly as you suggested... Thanks again....