I now have a 46" Sony Bravia HDTV, a Blu-ray player, and a Denon 5.1 Surround Sound System. Yet this evening, I was watching the first DVD in a 15 DVD set I ordered, "The Honeymooners: Lost Episodes 1951-1957", which comprises all the "surviving" LIVE Honeymooners sketches from DuMont's "Calvalcade of Stars" and CBS "The Jackie Gleason Show". The kinescopes are in varying conditions, from VERY bad, to decent... as I'd expect from live TV from the 50's preserved that way. However, I noticed the outline of Audrey Meadow's slip under her angel costume in the Halloween skit, so I think playing the DVD in the upscaling Blu-ray player on the HDTV DOES bring out at least "some" detail the TV audience in the 50's might not have noticed... although the STUDIO audience probably noticed if they were in the first couple of rows.
Point I'm trying to make is, everytime I tell someone MOST of my collection is black and white, early TV, monophonic stuff, they wonder WHY I upgraded. Well, it's for the few "modern" things I like... only explaination I can give! Also, some older theatrical films, like "Gone With The Wind", "African Queen", etc... look great on Blu-ray, as does older TV series shot on 35MM film, like the original "Star Trek", "Twilight Zone", "The Prisoner", etc.
DVD is still good for kinescoped shows like the set I just got, plus any pre 2000 videotaped series like "All in the Family", "Soap", "Welcome Back Kotter", "Monty Python's Flying Circus", etc. Blu-ray wouldn't help those shows to look better.