Hi, Anohito-san!!
Yes, Ginbura is still known, although it's because people in my generation are still alive!!
I'm pretty sure that there are young people who've never heard of it.
The people who used it most frequently are people in my mother's generation or older, when Ginza was "the only" fashion street in Tokyo and all of Japan. Now that the fashionable areas have scattered into Shibuya, Aoyama, etc., we don't hear anything similar any more. There's no "Shibu-bura"...
However, the merchants of Ginza are trying to strike back at the competition, and the street is undergoing renovation in the style of Fifth Avenue in New York, with Tiffany, Hermes, Louis Vuiton, etc., setting up shop there. Matsuya Ginza has transformed into one of the most fashionable department stores in Tokyo, and many chic boutiques and shops have opened, catering to more mature consumers than those strolling in Shibuya or Shinjuku. With this change, the word Ginbura has come back as well.
Personally, I do like Ginza more than Shibuya and Shinjuku where I go often for shopping (the reason being proximity), because the streets are wider and there are less shops for the younger folk blaring out jpop.