Obviously, a huge mistage, but one I don't think can be blamed completely on the Colonel. From what I understand, a cash-strapped EP was all in favor of it.
I couldn't begin to put a dollar amount on it, but most of the money RCA has made in the past 35 years has been from the 1956-1972 recordings. The 73-77 years are just not as well known to people. It also seems no strange coincidence to me that right after the deal, RCA begin packaging the earlier stuff more aggressively, for example the Legendary Performer series - using alternate and rare takes. The Colonel believed you did not dwell on the past, and did not see the value of those earlier recordings, or the attraction Elvis' early image still had with the public. As market-savvy as he could be, this was a big example of shortsightedness.