Extending copyright long after the life of an artist is bad economics. Because of the value of future money any revenue from future sales 30+ is essentially worthless now. So it doesn’t induce people to create more works of art and entertainment.
Is that if the price is constant over that time? Couldn't you just price the product to reflect roughly constant value, giving you linear return over time?
1.07^144 is 17,000.
So, if the album costs $10 in 2018 dollars, it should cost $170,000 at expiration.
Figuring in inflation and conservative returns give 5% per year, so 1125x markup. The album would only be $11,250 in 2018 dollars at term expiration.