The way he wass whisked away and kept away from the press, makes me suspect he had some form of a dementia event. After dealng with my late MIL, and FIL with this condition for 10 years, I know that it is pretty typical to have stroke like episodes, due to nuerological misfiring. Things will seem relatively normal, and they suddenly have no idea where or who they are.
Again, just speculative, but from what we saw of him this summer, I'd say the odds are decent of that prognosis, based on where I think he has progressed with the illness.