Dedicated red air
As threats become more advanced training to these become more difficult. More companies like Kestral and Top Aces allows us to training without having to loose our own jets to red air. While jets like F-5s are great they are very legacy and not to new threats. Getting newer 4th gen allows better training.
https://www.twz.com/air/f-a-18-super-hornets-eyed-to-replace-navys-remaining-f-5-adversaries