Trees are so valuable as landscape assets that they deserve care by certified arborists. The fee charged for professional consultation or service is far less than the potential catastrophe of losing a tree during a winter storm. Consider the tree's location. A tree that has the potential to fall, and has a target to hit, is considered hazardous. Any large dead trees within the area of a home certainly can be hazardous.
All trees have a finite life span, but the length of life depends on many factors.
A tree exposed to construction damage, poor root development, limited soil availability, and wounding from accident or vandalism has a far shorter life span than the same tree growing in ideal conditions. Stand back and look at the whole tree from a distance. The tree may leaf out late, drop its leaves early, or produce an unusual quantity of flowers and seeds. Angled or leaning trees should be checked and removed if they are leaning into the path of buildings or equipment or livestock. This may mean that the tree has an unstable root system.