Originally built as a supersonic strategic bomber for delivering nuclear strikes on Moscow, the B-1B Lancer has played a variety of roles for the Air Force in its nearly 30 years of service. And thanks to a newly upgraded cockpit—including four multi-function color displays and a modernized Fully Integrated Data Link (FIDL)—the B-One "Bones" of the 7th Bomb Wing are expected to remain in service into the 2030's. [Wikipedia - The Aviationist]
Nice. Even more amazing is the B-52. Entering service in 1955, the last one was built in 1963 and some are still on duty. It served as the primary strategic bomber throughout the Cold War, implementing one branch of the "triad" system of Mutual Assured Destruction, the nuclear deterrence strategy that is still in effect. We are now well into our third generation of B-52 flight crews; the grandchildren of original flight crew members are now flying them. Three Air Force bomb wings still fly some 76 operational B-52s, about 10% of the total built. Upgrades currently under way are expected to keep at least some of them flying through 2040. The BUFF is one amazing airplane.