As reported by 1080eye, Congress' DTV bill would not allow cable companies to downgrade digital channels to analog broadcast, meaning cable customers with analog televisions would need to upgrade to digital set top boxes as well.
My reaction to this is it's a real non-story. The cable companies don't want to broadcast in analog, first of all it's insecure, (look at all the "special" boxes you probably get email offers for daily) and it uses a lot of bandwidth they'd love to have for more Internet, VOD and HDTV offerings. Plus it's cheaper for them when a customer wants to upgrade/downgrade service, you just flip a switch instead of sending a technician out to the home to change the filter at the pole.
Take a look at the next flyer you receive, in most areas the cable company is offering a discount over analog cable pricing in order to move digital boxes and their assortment of additional features into the home. They are more than ready to pull analog support as soon as possible. This could be reported in multiple ways, if the bill did not have such a provision, I'm sure there would be an op-ed column ranting about how Congress is in the cable companies pocket by forcing people with older TV's to get cable TV.
I think it's better that it be across the board to avoid confusion, DTV is coming, and you'll need a new digital set, or a set-top box of some kind to get television reception, period.