I haven't heard any news about any sort of mental decline or difficulty in communicating (the media would of course gleefully report such news since he has an "R" next to his name). Physical shape is another matter, though, it's a miracle he's still alive at this point and a couple years back they had to do some kind of creepy surgery where his blood circulates without a pulse.
. I do think Dick Cheney would have no problem making a statement about Princess IF he felt inclined to do so. He did issue one just recently when Donald Rumsfeld died.
My gut feeling is he knows she's buried herself in a hole and keeps on digging.