US Navy trainer economics and an F/A-XX prediction

Why are manufacturers reportedly leaving the Navy's jet-training programme, and where might F/A-XX lead?

The trainer's expected financial return is judged insufficient for its requirements. Boeing is separately predicted to win F/A-XX.

The audience question reports that Northrop Grumman and other manufacturers have left the Navy's jet-training competition. Insufficient financial return and unrealistic cost expectations are the proposed reasons for those withdrawals. Boeing is separately predicted to win F/A-XX. The reported withdrawals remain the question's premise, and the Boeing selection remains a forecast.