Today’s biggest pop music draws, those capable of filling stadiums and charging big ticket prices are getting on in years. Younger artists of their stature aren’t coming along, and presenters are worried. “I don’t know what the Social Security plan is for those of us in the concert industry who will be waiting for the Stones and McCartney to still be touring in 10 to 15 years. But we need to worry about how to fill those arena, amphitheater and stadium dates with an artist-driven or event-driven tour.”