An F-22 with F-35 tech and a super-powered F-15 Eagle? The Air Force isn't interested yet.
Almost since the day the last F-22 Raptor fighter jet rolled out of Lockheed Martin's assembly plant, the U.S. Air Force has been making plans for its successor—a "sixth generation" fighter aircraft to continue the U.S. military's dominance of the air.
In 2016, the Air Force issued its "Air Superiority 2030" strategic plan for the next 15 years of air combat capabilities, which included a call for developing a "Penetrating Counter-Air (PCA)" aircraft. Essentially, the military wanted a fighter capable of surviving in an advanced, hostile environment while taking out enemy aircraft and air defenses and acting as "a node in the network, providing data from its penetrating sensors to enable employment using either stand-off or stand-in weapons." The U.S. Navy is looking at similar capabilities for its carrier-based air operations.
The F-35 Lightning II is not an air superiority fighter aircraft. While it can dabble in that role, it was intended to be a "strike fighter"—a fighter-bomber workhorse meant largely to take on ground targets and defend itself as necessary. The F-22 was built for such a life, but only 187 operational F-22s were delivered before that program was shut down in 2011. Since, advances in foreign aircraft, air defenses, and detection technology (including infrared systems and, potentially, "quantum radar" being developed by China) may have begun to put a dent in the F-22's superiority.
Designs for a successor aircraft to the F-22 are still highly conceptual at this stage, and it could be a decade or more before a contract is even awarded to build the next-generation fighter aircraft; that has the two major fighter aircraft manufacturers—Lockheed Martin and Boeing—feeling a little itchy. Both have been pitching interim plans to the Air Force that wouldn't require a long lead development cycle while helping to beef up the Air Force's air superiority capability much sooner. The Air Force, however, has not yet been hooked on either option.