If he’s not dead dead, which admittedly seems like it would hard to keep secret for a month and a half, it seems pretty likely that he knows he isn’t fit to serve and is simply waiting on announcing that until it’s too late for the people of Kentucky to have a say about his successor. Which would, as many have noted, be a perfect way for this ghoul to end his career, fucking over his constituents one last time on his way out the door.