If its a fact that composites degrade with age, then there must be an engineering analysis of how much, how fast, and to what degree that decomposition occurs. If you know of such study then post a link if available, otherwise I suspect you are posting internet facts, which may or may not have a basis in reality.
Any just to be clear, I do not own a CF bike, nor likely will I. I prefer the look and ride of classic level top tube steel bikes. But that preference does not lead me to speculate that CF bike are going to catastrophically fail at some unknown time in the future due to unqantified aging of the construction material, based on facts gleaned fro unspecified internet sources.