Analog TV has long been on its way out. The eventual goal for all cable subscribers, and the FCC is to have anyone viewing TV to be doing such on a digital display - or, at least, have some form of digital to analog converter in their home. That will happen as an eventuality no matter what, but now it may take longer than the cable companies originally wanted.
The FCC voted unanimously that cable companies will be required to continue to offer local channels in analog until at least 2012, 3 years longer than originally planned. The FCC's justification for this is that a large amount of homes (40 million or more) still have only analog TV sets. While many of those could have some form of DAC (like a cable box) inside, there are still many who may be relying solely on analog signals.
There are some exceptions, for small companies, but for the most part it has given anyone not wanting to "go dark" in 2009 3 more years to purchase or otherwise acquire a set capable of receiving digital signals.