F-15 EX and F-35 are short legged too, one have great kinematics with a design of years 70s and not stealth and the other will never have his full capacity with medium kinematics capacity and stealth , do you realy thing this combo is the air dominance of decades to come ? China are working on J-20, 6th gen fighter , capacity in space and a lot in the Hypersonic and may be the SR-72 will be Chinese instead of US. Boeing invest 1 billion in a new facility and you imagine USAF say I don(t want new aircraft, what will be the credibility for the futur ?