Chad is right. There is no rational business case analysis that would lead Dish to remove SD channels.
Dish should remove all sd stations, its 2014. Just offer HD standard, nothing special about HD anymore.
Chad also mentioned people who only have a tv with a rf-input. Lets look at this logically. How many people have as their main tv a set that only has a rf input, then how many of those people pay for tv from a cable or satellite provider, and then how many of those people couldn't afford a cheap used set off of craigslist, or have a friend or relative give them an upgraded set. That group must be pretty tiny.
Sounds like you're just making it up as you go. Why do you think that group must be "tiny"? Many people have rf-only, cable or satellite connected TVs that have no idea what craigslist even is (see...I can make it up also ). My 85-year old mother is one of them, but I can come up with more than a dozen in my extended family off the top of my head. A lot of these (...again, making it up), if forced into a HD upgrade would just pick up the phone & call the cable company.
I'm sure Dish has a bunch of smart people running alternatives through spreadsheets considering how and when to proceed with transitioning from SD to HD, and they aren't making it up.
You have to realize that folks you see on the internet & on forums like this are a self-selected sample that in no way (yet) mirror the public at large.
And that group that I talked about must be tiny, simply by the fact that tv's that only have a rf input are ancient and most likely are secondary or tertiary sets. So all of these people in your extended family have rf input only tv's as their main set, and can't afford to upgrade via craigslist? WOW, the economy is in worse shape than I thought.