Jerry is getting is too old. I am not an ageist. I have seen people, like my mother, working into her late 80s with no apparent signs of slowing down, other than her hearing. But for some people, their brains go first and earlier than for others. The people around them may not notice because it is the boiling frog scenario.
Jerry Jones is showing the signs. The rambling answers to simple questions, the longing for the good old days, the irrelevant stories that only he cares for, and a certain incoherence in his thought processes. Subtle, but when compared to normal people it becomes more obvious.
Unfortunately, as he goes down, so do the Cowboys. But I really believe he is only another 2 or 3 years from being out of the picture completely. Once the decline starts, it doesn't stop. It accelerates.