Why does my front end shake at 60mph or higher/

Your tires may not have been speed balanced for higher than 60mph. They usually do them for 70mph. What kind of shaking is it doing exactly?

Q7 suspension is very reliable, haven't typically seen any worn components in the front suspension. Most Higher speed vibrations are due to improperly balanced wheels. Many tire stores only balance the insde edge instead of dynamically (inner and outer edges) because they don't want to or can't put weight on the outer edge due to the design of the rim lip. If you only feel the vibration under braking it is caused by brake rotor surface variations, commonly refered to as (warped rotors). If you feel the vibration on acceleration and it goes away when you lift off the throttle it is bad axle joints or driveline wear. These Chassis' have issues with center carriers failing mostly on the older Touaregs and Porsches. Haven't had to do any Q7s yet but they are getting old enough now.