The 2012 date staticMHS mentioned pertains to the expectation that the
FCC placed on legacy MSOs (like Comcast), regarding provision of
local broadcast channels via analog. It does
not pertain to any
cable channels.
Also, the
FCC, in a rare pro-cable decision, outlined
two ways that MSOs could comply with this requirement: Either provision of analog signals in the coax,
or by provision of a set top box that converts digital cable (QAM) to analog. So nothing is really guaranteed. Like I said, a very rare win for cable.
The latest information from Comcast is that their intention is to have about
half the country converted over to all-digital-cable (all cable channels via digital) by the end of the year. If your television doesn't have a QAM tuner (not all HDTVs do -- over-the-air
HD is not broadcast using QAM, but rather using
ATSC 8VSB), then you will definitely need to rent a cable box to continuing getting cable channels, once your system is converted to all-digital-cable.
As TonyT alluded to, many systems already encrypt digital cable (to discourage cable theft), so even if your television does have a QAM tuner, that probably won't be much help, because your television probably doesn't have a CableCARD slot, so it won't have any way of decrypting the broadcasts.
In many places, Comcast has already discontinued offering "Standard Cable" (their top-level analog service) to new customers. The only analog service they currently offer new customers is limited basic; if you want any cable channels, you are now required to select a digital package. Expect that they will be phasing out the analog packages they have, above limited basic, for existing customers, as the next couple of years go by.
So while the over-the-air
digital transition, "
DTV 2009", will not affect cable customers, cable's
own digital transition possibly will.