Stairway to heaven?

There are some beautiful mature trees on my regular walks near home. I have noticed that more of them appear to be succumbing to various forms of bracket fungus.
The first external symptom of bracket fungus infection is often the appearance of the bracket-shaped fruiting bodies on the trunk or main branches. These can be up to 60cm (2ft) in diameter and may be annual or perennial. The bad news is that by the time a bracket appears there will usually have been extensive heartwood decay. Since decay weakens the wood the tree will be compromised to some degree.
I have no idea if the recent wet weather has contributed to this problem or if it has always been there, I do hope that it's not getting worse as it would be a real shame to lose these fine trees.