After ~18 months of delay there's finally a replacement for the aging T-38 in the works.
https://www.defensenews.com/breaking-news/2018/09/27/reuters-air-force-awards-9b-contract-to-boeing-for-next-training-jet/
https://www.defensenews.com/breaking-news/2018/09/27/reuters-air-force-awards-9b-contract-to-boeing-for-next-training-jet/