Well US 6th generation fighter aircraft are already well underway. Some of the systems we will be developing at solid state laser weapons that can create a sterile sphere of safety around carrier fleets, shooting down both aircraft and incoming missiles, or damage weapon systems with microwave radiation.
Another new development would be a way to capture the heat energy created by the jet turbine, and instead of off-loading it and hiding the heat, the heat energy would be transformed into another power source.
Boeing is looking at a plane without the rear vertical stabilizer, which would also lower its profile and increase its chance of surviving attack. It would also give it a smaller radar cross section. It might actually make it less maneuverable but it makes it less vulnerable as well.
The F-22 was a disaster cost wise and in sourcing. Of the 187 planes built only 125 are combat ready and most of the problem is coding and upkeep. The F-22 is also a difficult plane to maintain and lots of them are down at any time.
Here are renderings of the 6th generation fighter, the F-XX