As Anders already mentioned, the wheels on most (all?) aircraft are completely independent (well, except for friction) of the actual driving force of the aircraft. So, thrust will still push the plane forward, and the plane will still takeoff when it reaches it's normal speed relative to stationary ground. It's "speed" in reference to the moving treadmill would be wholly irrelevant (unless there was some mechanism to cause enough friction to prevent the plane from moving forward at a speed fast enough relative to stationary ground to takeoff, like maybe if the treadmill was moving unrealistically fast and the wheels just couldn't physically keep up, they are very heavy wheels after all).
As Anders already mentioned, the wheels on most (all?) aircraft are completely independent (well, except for friction) of the actual driving force of the aircraft. So, thrust will still push the plane forward, and the plane will still takeoff when it reaches it's normal speed relative to stationary ground. It's "speed" in reference to the moving treadmill would be wholly irrelevant (unless there was some mechanism to cause enough friction to prevent the plane from moving forward at a speed fast enough relative to stationary ground to takeoff, like maybe if the treadmill was moving unrealistically fast and the wheels just couldn't physically keep up, they are very heavy wheels after all).
