Nothing. The current analogue signals will be broadcast just as they are today until the transition to DTV is complete, at which time they be terminated. In the US this is legislated to occur February 17, 2009. In Canada, the date has yet to be determined, but will certainly be well after the US closure of analogue television. As part of the transition, it is expected that low cost converter boxes will soon be available to allow current analogue receivers to receive the content of DTV signals, but of course, at the lower quality inherent in the analogue receiver.