ISS will be manned for as long as it is safe to do so. Obviously if any large parts fail and that causes it to be unsafe to remain then they'll have to leave as there'll be no shuttle to bring up replacement parts, but most systems have at least one redundant backup, and often two, so hopefully it'll be a while before that happens. Smaller parts can be shipped up via soyuz (Russian), progress (Russian), ATV (European) or HTV (Japanese). ISS has a design life until at least 2015, which you may feel is short, but bearing in mind that it should have been completed several years ago, is not so bad.
As for the shuttle, scrubbed as expected. Based on past comments, my guess is it'll be at least a few weeks before they try again (this launch window closes in a few days anyway).