In doing some additional research, my current theory is that you can still subscribe to AT packages and have $10 TurboHD channels added. However, you can't subscribe to the HD-only turbo packages. I came up with that theory by looking at this page:
DISH Network -- Dish HD
Don't know if I"m right or not though.
DISH Network -- Dish HD
Don't know if I"m right or not though.