It might be a good idea to get an opinion from someone knowledgable regarding mechanics, arm action, arm speed and other things that relate to projection.
There can be a big difference between two 16 year olds who both throw 79-80 mph.
No one knows for certain what will happen in the future. So much depends on effort and desire. However, there are several "clues" that provide for a more educated guess.
The first time I ever saw "Bums" son pitch, I knew he was going to gain velocity if he really wanted to. also I was pretty sure he wanted to. Therefore I liked him more than many pitchers who threw harder at that time. It was because of all the other things rather than lighting up the gun at that time. That would come later.