The F-15 Eagle, arguably the most successful fighter jet of the modern age, could be in for an early retirement with the US Air Force thanks to skyrocketing upgrade and refurbishment costs.

In a hearing before the House Armed Services Committee, Air Force and Air National Guard brass informed the panel that a plan was recently formed to retire and replace the F-15C/D variant of the Eagle far ahead of schedule by a matter of decades, though no decision had been made on that plan. While the Air Force did plan to keep the Eagle flying till 2040 through a $4 billion upgrade, it was recently determined that a further $8 billion would need to be invested in refurbishing the fuselages of these Eagles, driving up the costs of retaining the F-15C/D even higher than originally expected — presenting what seems to be the final nail the Eagle's eventual coffin.

So, what will the Air Force likely do to replace this 40-year-old wonder jet?