To some extent I agree w/you but I also know that many older people use mp3 players. Take a look around any airport waiting area. In addition, those of us in our 50s now have no intention of not using these players (or whatever new technology there is 20 years from now) just because we hit 70.
When I talk to undergrads about technology I always have to tell them not to be ageist in their thinking. 20 year olds are not the only people using computers and music players. They often seem surprised.
My own personal failure in this area is seeing truly senior people using cell phones. I don't know why, but it always seems odd. Maybe because being on college campuses I just see so many young people with them.