Given that digital switch-over for TV has only just about finished, and DSO for radio isn't likely to happen before 2015 at the earlies, I can't see this happening anytime before 2020 at the very earliest, probably even much later than that. Plenty of time for fibre to become the standard and the freed up spectrum to be used for more efficient methods of wireless transmission, it certainly won't bring the internet to it's knees.