Anthologies, bootlegs, and rehersals dead and gone?

[Elspode]

...and his father said the same thing about Glenn Miller, and his father said the same thing about Al Jolson...and so on.

Those who have a fanatical interest in (place performer name here) will always have some interest. As they age, they will develop nostalgia for the media of their youth (there's a reason we are seeing a bunch of lameass movies made from old TV shows, 80's cartoons are being recycled, and the toys of those who now have their own children are coming back onto the shelves).

Once the kids who can barely afford to steal the mp3's have grown into adults with disposable income, products will arise to deprive them of some of it. Anthologies, live albums and other such rarities/oddities only come into existence when there is a big enough market for them.