Okay I've asked enough people to get an overall idea of what Comcast will be doing. First in markets that have enough analog only customers that make it harder to cut off all analogs except 20ish channels (ie Chicago) they will be creating a new standard cable lineup including what Chicago has on analog still plus the top 20-25 channels such as ESPN, TBS, USA etc. Beyond those 40-50 analog channels that will stay analog the remaining 15-25 analog channels will become digital only and will be included in the digital starter package which is the same price as standard cable (without digital box fees). Most markets will have 20 analog channels removed which will free up room for 40 new HD channels.
This will allow most markets the ability to carry an extra 40 HD channels which will be the most watched of all available new HD channels. So for any new HD channels beyond those 40 HD channels they will start using SDV. I've also been told that they are working on a solution for SDV with cablecard devices (including TV sets and the Series 3 HD Tivo). They expect to have this solution available by the time they need to use SDV for HD channels beyond the 40 limit which they don't see as being a problem until 2008. They also said that they don't believe SDV will help much for channels such as ESPN HD, Disney HD, USA Network HD etc as each hub is highly likely to have multiple customers viewing these channels.
Where they can save that bandwidth is with channels that are less likely to be watched during high volume times such as primetime and those will be placed on SDV. Also if viewership ever days change on channels they can always switch channels around between SDV to/from main channel lineup.
The bottom line is that I've been told that they will carry pretty much all new HD channels DirecTV will carry and they are working on the contracts as we speak. They are just taking longer because most major new HD offerings are coming from the likes of NBC Universal and Disney so they aren't just working a contract for the HD channels they are also working on the On Demand contracts. For example they are working with Disney to get all of their upcoming HD channels but they are also working to get HD carriage of On Demand content from Disney channel and ABC network content. They are working with both ABC and NBC to get the same type of deal they have with CBS. This means they want both SD and HD primetime programming via On Demand available at no extra cost to all Comcast customers.
I know this post went quite long but I wanted you all to have the full overall direction Comcast is moving towards.