Question: What 5th generation USAF tactical fighter built by Lockheed Martin and Boeing will remain in service alongside the new sixth generation fighter?

Related documents: [0]  [DOC] The Lockheed Martin F-22 Raptor is a fifth-generation, single-seat, twin-engine, all-weather stealth tactical fighter aircraft developed for the United States Air Force (USAF). The result of the USAF's Advanced Tactical Fighter program, the aircraft was designed primarily as an air superiority fighter, but also has ground attack, electronic warfare, and signal intelligence capabilities. The prime contractor, Lockheed Martin, built most of the F-22's airframe and weapons systems and conducted final assembly, while Boeing provided the wings, aft fuselage, avionics integration, and training systems. [END] 
[1]  [DOC] A sixth-generation jet fighter is a conceptualized class of fighter aircraft design more advanced than the fifth-generation jet fighters that are currently in service in the United States and in development in other countries. The United States Air Force (USAF) and United States Navy (USN) are anticipated to field their first sixth-generation fighters in the 2025–30 time frame. The USAF is pursuing development and acquisition of a sixth-generation fighter through the F-X program to complement existing platforms in service such as the Lockheed Martin F-22 Raptor. The USN is pursuing a similar program called the Next Generation Air Dominance, likewise intended to complement and/or replace its existing aircraft such as the Boeing F/A-18E/F Super Hornet. [END]  
Answer: Lockheed Martin F-22 Raptor
Lockheed Martin F-22 Raptor