The cards closed will continue to age. But drop the avg age now. However they should not be reporting a balance in closed status. That is a very bad thing. You will need to contact them to delete the card or at least report it as $0 balance. Other wise it will work against your UTL and look bad to lenders. But it being closed with $0 bal is perfectly fine.
If anything in 4 or 5 years it will help keep up your average age until it falls off in 10 years.