Airplanes do not fly forever. At one point, they get too old, then they get decommissioned, after which they are recycled or disposed of. The case of eagles is a bit similar.
Eagles can die naturally, from old age as many other animals do. But in recent times, dying of non-natural causes has become more common.
One disease that is known to kill bald eagles is the West Nile Virus. The virus is of the flavivirus genera, and these eagles are known to get it when they eat infected prey.
Wind turbines are one of the most significant causes of unnatural death in eagles. In their flight, some eagles get caught in the blade of the turbine and are killed.
Eagles are apex predators, so they are not preyed on by other animals. But while mature eagles have no predators, their eggs and nestlings can fall prey to predators.