Just a couple years ago I had to cut down what was a healthy, large 60+ year old Ash tree because of the stupid Emerald Ash Borer. It was a gorgeous tree with a huge, solid shade. Then all within 3 years it went to hell.
Just a couple months ago I had to cut down one of my Dogwoods because it hollowed out and was in danger of falling over even though it still had a pretty healthy canopy.
I've been having terrible luck with trees the last 15 years.