Jillian Cohan has an article in The American that notes that the biggest touring acts are all aging, and wonders where the music industry is going to get it's future cash cows. I think they're going to have to realize that those 60s-70's bands carved followings from a Boomer population that was a freak of demographics. Not only is the music business fragmenting, but the sheer size of the consumer market isn't going to be what it was. Music as a big financial business is a relatively recent phenomenon, and it just isn't going to be a license to print money anymore.
I think Disney is showing one model by developing acts through their various enterprises.
It's also worth noting that those old acts are exceptional, the ones who managed to keep it together long enough for their fans to accumulate the money to spend on those tours. There will be others: it'll just take time.