If there are indeed 20+ milllion D* receivers in the field that cannot do MPEG4, then I agree that it will be a long time before MPEG2 goes away.
At best, you are talking about D* shipping out 20+ million new receivers directly to homes for customers to swap. And millions of customers won't be able to do this, so that will require millions of service calls.
If D* can get the average cost to them for a swap down to $100, you are talking about a conversion cost of over $2 billion dollars. And I seriously doubt they could hit that figure. If it is 25M receivers at an average cost of $150, that would be $3.75B.
If they were serious about doing this anytime soon, then they should have started shipping receivers that could all decode MPEG4 a good 2-3 years ago. For their conversion problem only grows larger every day.
I suspect somewhere along the line they decided that they'll eventually phase out MPEG2 HD channels and deal with that rather small conversion, but that they are indefinitely delaying converting SD channels to all MPEG4.
They sort of did do that, remember for the last several years now there has been a push to get all the people that use the NFL ST and MLB EI's to move to mpeg 4.
Granted thats a small portion in the overall scheme of things, but they have started to move that way. Your high end customer has already moved that way. Friends of mine who are NOT Sports fans at all and do very little other than the normal everyday viewing have been moved to H and HR recvrs now, without owning any HD sets, this it to D*'s advantage as well as thew sub getting into better equipment.
When the avg. sub does get moved to mpeg 4, most have NO iodea that the change is being made, most just hear that it's the new set up and thats that.