I would presume that McNally was well-known enough that at least some of the obit had been written beforehand, but it is a bit oddly constructed. It flows in spurts, and the works that are discussed in more detail aren't necessarily the works that had the most impact or the best received.
It is interesting how Angela Lansbury changed his life, although they were not close friends. I wonder if she ever had that conversation with anyone else. I would love to hear her perspective on it.