You can still get all of these corals. You are just likely going to have to order them or make a special request since collectors, wholesalers and mari folks are cranking out rainbow tenuis now. Blue/white tenuis is still available on every wild collection sheet that I have seen. It isn't like the ocean doesn't have them anymore. Just remember that some of the reason why these have died out in captivity as care changed with lower/shorted spectrum, higher residual no3 and po4 to keep dinos/cyano at bay and smaller, less stable tanks are common. Captivity has selected some of these for limited hobbyists. It is not like they are not still beautiful or anything.
If you want them in captivity and not wild, you will have to seek beyond the internet. I have recently found some of the first generation of Tyree LEs (like back when he was not a joke) and it was a guy who has long lost the taste for participation in online stuff but had a wonderful tank. I met him through a friend. There is even some OG Leng Sy floating around Denver, but you usually have to go offline to find it too. Found some 20k and 30k too with real lineage. I even got some OG Purple People Eaters for a small softie tank that I started recently - I remember shipping these in thermos during the warmer months.
I still have not found any Soda Popinski for Tim, but I hope that he found some.