First of all, vinyl is still relatively niche in absolute terms. Second of all, the popularity of vinyl, such as it is, has absolutely nothing to do with availability. It's largely driven by a kind of retro nostalgia (as the technology itself is, of course, inferior from a technical sense of faithful reproduction) plus a desire for personal physical ownership of something.
> It's largely driven by a kind of retro nostalgia
Incorrect. The reasons why vinyl specifically is still relevant (as opposed to any other "retro" audio format) are technical.
Vinyl avoids compression issues by design. (Compression both in the computer science sense and in the audio engineering sense.)
I was a zealous collector of records when we made the switch to digital audio. And let me tell you, there was a significant artistry to the thing: a vinyl record was a standardized work of art. Every album cover was the result of careful design, photography, layout. The inner sleeve oftentimes contained more art, or if we were lucky, all the lyrics we wanted to sing along with. The record label itself, a masterpiece of design. All the smells and all the feels of merely collecting vinyl--even without playing it--are indescribable today.
When CDs came into the market, they were horribly clacky and just clad in layers of tacky plastic. The album art was shrunken, misshapen... and the objects themselves stank of polycarbonate, rather than delicious vinyl. Sure, they sounded great and they lasted a long time, and maintenance was dead simple. But so much artistry was lost. I was still collecting lots of CDs when purely digital distribution hit us, but by then, the smells and feels and experience of collecting vinyl were distant memories.
And that entire experience may be why people argue for the technical superiority of vinyl recordings, and analog tube amplifiers. Because it was all self-reinforcing, and it all fell apart once the clacky, tacky, plasticky CDs took over.