I think this is a misinterpretation of the original 105 press release when E* announced that they were planing on an eventual up to 50 HD channels on 105 SuperDish, however a lot has changed and I do not think it was ever meant to imply an all HD AT50. Besides few if any of those channels currently in AT50 (AT60) even have plans for HD anytime in the near future. This report on that other forum is pure misinterpretation and wishful thinking fiction.
There is not enough content for it yet. And even the announced upcoming channels would not comprise a top 50 package.
I think people are confusing that Dish said with the SuperDISH could offer up to 50 HD channels by the end of this year. However since the HD plans for the SuperDISH have been scrapped for now, it thros a monkey rench into things.