It's amazing to see those trees keep going and going. Around here, when a tree starts to die off in sections, we take it down. Looks like those have been dying for hundreds of years, but left to their own devices and they just keep hanging on. Some of them look terribly unhealthy. Like the Cage Pollard Beech which is about 95% rotted out and supported only by a few inches of live growth here and there while the rest of it is disintegrated and long gone.
I guess once you don't cut it down and enough time goes by, it's historical and then you wouldn't dream of cutting it down.