By law, terrestrial MVPDs are required to provide local, over-the-air channels, in-the-clear (i.e., without a cable box). In addition, most larger, terrestrial MVPDs are committed to providing those same channels in analog through June 12, 2012.
Those are likely to be the only channels that will be available to you.
Not only would premium channels not be accessible without a device that supports decryption, but generally expanded basic cable networks, such as ESPN, TNT and Disney, are likely to be inaccessible as well.