''So, by artistically relevant I mean Elton, Paul, Billy are no longer contributing artistically in a meaningful way. ''

It depends what you want from your music doesn't it. Most of the time all I want is to be entertained by something that I enjoy listening to.

As long as an artist is doing that for me then I'll carry on listening, buying their music, going to their concerts.

As long as people are doing that why wouldn't they keep performing?

Whenever someone new comes along, if I like them, I'll listen and buy.
If I get fed up with someone then I'll stop.

I don't care whether they're 'relevant' or not. And they're certainly not stopping new talent coming through.