Your son can only control or affect his personal development. There is a lot more to being successful than exit velocity in a controlled environment. There is a significant amount of physical and mental development between the age of 14 and 18.
If you want to track development then benchmark where your son is now on the metrics that many look at such as the 60, throwing velocity, how far the ball travels off the bat, how much carry on throws from the outfield, etc... then compare where your son is in six months. Generally you see incremental jumps in skill as strength and timing improve. Obviously, the measurable tools have to translate into in game execution.
I would not bother being concerned with comparing your son to others, you can't control what others can do. The most impressive player I ever watched was a 12 year old who cleared a 300 foot fence in a game. Tremendously impressive player that had a good high school career but didn't stick with a D III school. I know another player as a 14 year old who could not stick with most travel teams. He grew to 6'5 and is a DI pitcher who is a very good pitcher. He simply did not have any abilities at a young age that made him stick out. He never pitched in a Varsity game until he was a Junior. From Junior year on he was one of the best pitchers in the area.
There is simply no way know what will happen between 14 and 18.