Well, no worries until April at the earliest. Nobody who follows cable/satellite TV "news" (ala http://dslreports.com
for several TV forums or AVSForum) should NOT be surprised that Comcast is making this move sooner rather than later -- it was always going to happen, it was just a matter of when.
All those analog channels are taking up a lot of "room" -- digital takes up much less and when Verizon can offer 100+ HD channels (and 100s more of SD channels in digital format) to Comcast's measly 36 HD channels (in my market)... well, it's kind of a no-brainer. I believe satellite has similar offerings (100+) as far as the number of HD channels...
So every TV without a QAM tuner (different than the OTA ATSC tuner), that is, all the old analog TVs will minimally need a small digital tuner box to get anything about #30 or so. Comcast is offering three for free just as Verizon did as the made the move to all-digital.
I wonder what channels Comcast will provide over QAM that aren't encrypted -- that's the real question
(any encrypted channels, HD or SD, will require a box).
Check out: http://www.dslreports.com/forum/tvcomcast
if you have too much time on your hands