I suggest looking at the persimmon flowers before doing anything else. You can see if they are male or female. I once bought 6 grafted persimmons, and one ended up being a male. This happens when a shoot from the rootstock comes up right at the same point a graft was made, and the person didn't notice it when the tape was removed.
It's not unusual for a volunteer female persimmon to remain fruitless for that length of time, but grafted persimmons that are healthy will usually be fruiting by then. For female persimmons to produce fruit with viable seed, they need a male, but they produce fruit with no (or unviable) seed without a male. This process is known as parthenocarpy. I have several 90 chromosome persimmon varieties with no 90 C males in the area, but they still produce good fruit.
Unless your pears are absolutely horrible, I would wait until later before doing something drastic. This year has been the worst for disease that I have ever seen in my life. Even the most resistant apple varieties such as Liberty, Enterprise, etc. are showing at least some signs of disease. However, it is nothing to get overly alarmed about.