I really wish I could get a simple message across to him: "Georgie 'ol boy, your legacy you leave on this Earth with consist of nothing at all except that because of you, in the future, no one ever begins reading a series until it's completely written. Therefore authors will suffer as no one will dare try an author's work while they finish writing the series. IF you don't finish these last two books before dying."
I feel like that might get to him and spur him on to just hammer them out.