Aging movie stars ...

Two ideas:

1. Compare pictures of how movie stars were aged to look older in old movies to how they currently look; now older. I.e. James Caan in 'For the Boys' to how he looks now, etc.

2. Have a bunch of young actors shoot the flashback scenes of a movie now and then wait 10 years to film the rest, Or cover the bases by filming 2 to 3 actors in each role so you can use whoever became the better actor down the line.