Isn't one of the fan made DVD's allegedly sourced from a broadcast master found in the basement at a CBS affiliate?
Lucasfilm does not pretend the HS doesn't exist. The characters have listings on the official site, and Hasbro released a Boba Fett based on the cartoo segement.
If they finally decided to officially release it, there might be music rights to sort out with Jefferson Starship, etc. Nobody was thinking of a video release back in 1978.