I'm not sure that we do. We did when the JSF project that produced the F-23 was launched, but that was in 1993. More recently, the 6th gen fighter project that would be the follow-on seems to have been abandoned by the air force in favor of a strategy of disaggregating into independent component upgrade projects; for the attack role, it looks like the real replacement for existing manned airframes will be drones (the MQ-9 Reaper seems to be taking that role now, and the air force is training more drone pilots than anything else.)

> Why not make a generation of hyper-advanced missiles? It has got to be cheaper and easier (you don't need to visualize anything, because it is a computer) and you wouldn't even need active lifesupport.

Drones carrying the same type of missiles a manned attack plane would carry are cheaper over time and more flexible in use than "hyper-advanced missiles" that fly the whole mission themselves and are consumed each flight.