That's already happening: just look at the origins of top British musicians and actors now vs 3 decades ago - the age of stars hailing from the working class like David Bowie and Michael Caine is well and truly gone.

Like many other things, the filtering out of anybody not from the upper middle and upper class happens very early on and often even upstream from them starting their careers: it's simply not affordable for them to go live in the places were things like good theatre academies and the best opportunities are, especially with the insane housing costs there.

On top of that there's also the heavy nepotism and cronyism in those environments, especially theatre, so somebody not from that environment already and whose parents don't "know somebody who knows somebody" there are pretty much screwed.

Losing money to piracy is well behind those things in affecting working class kids' chances at making it big in the arts, especially given that the stage at which they are being blocked from progressing is one where they're not famous and make most of their money from live performances, were piracy has no effect or can even have a positive effect if it helps make them more known as artists.

Mind you, I think it's the morally right thing to do to pay those who need the money when you enjoy the product of their work, directly and bypassing the industry leeches which just leverage their control of distribution to extract rents, I just disagree with your theory that it's somehow relevant for the arts being accessible for people not from well off origins, since my own observations when I had some contact with that world back in the UK and being interested in the subject also read about it, were that the causes of the massive fall in people from the working class in the arts in the UK were a cross between broad structural problems that pretty much stopped social mobility in general there and the nature of the arts as a very tough area were a handful of people make most of the money whilst the vast majority of artist spend years trying and failing barely capable to survive (nowadays not at all unless they have the bank of mommy and daddy to support them).

Paywalls only move this to the consumer:

If art doesn’t make you money, only rich people can make art.

Under the current system, you can make money making art, but only access it if you’re not poor (or pirate it lol).

Either way, much of art becomes an image of the experiences of rich people, either through the artists themselves or the audience.

A more fundamental change is needed if you really want to solve this issue.

If your pension plan is a rope, might I suggest a guillotine instead? or first? Get rid of as many top hoarders as you can.

I remember the looks I got at a goalsetting workshop when they asked, "What would you do if you had six months to live?" and I said, "Killing spree."