varies from car to car. i would expect 50 to 60,000 miles from a wheel bearing, particularly the contact bearings (press in type, mostly on front of cars) maybe not so much from a tapered roller bearing (at the rear of old corsas,golfs). as these require to be greased regularly.
There's no answer to your question, especially not knowing the quality of your car, they can last the life of the car or give up after a few thousand miles.