You don't see my point. If the oldies never have skill drops, their experience will continue to increase. So they are still getting better, even if you can't train them.
Another point - eventually we'll have an oversupply of players if they don't get old and die.
Plus it is very unrealistic. How many 40 yr olds play in the NBA? For that matter, are there many players over 31? Do they still play like they did in their prime?
Run of the Mill Canadian Manager