"And what advanced systems are present in the F-35 which can't be retrofitted into the F16s and F15s." Those are both 45+ year old airframes as well. You're go

"And what advanced systems are present in the F-35 which can't be retrofitted into the F16s and F15s." Those are both 45+ year old airframes as well. You're going to have to upgrade to something new eventually...