IME, the consolidation of radio, changes in taste around live music, and the dissolution of paying for recorded music all worked to get rid of that group of folks.
But that doesn't mean that I haven't played with a lot of folks who are now in their 70s and 80s who made a good living playing music for folks.
Perhaps the artist in the article could similarly pivot. At least, that seems to be the main way to stay in the industry if you are unable (for whatever reason) to attain commercial success.
Also, the comment you replied to said that those names he mentioned were the relatively famous ones. The ones who are less famous than that will not have the success you mentioned. They will simply be people who had mid-level success in an industry that could support them.