I would not worry about anything at 15, especially if he is still growing and getting through any awkward stages. Work on speed,strength, conditioning and of course skills. If around, get on the best travel team where he can play. Riding pine does not garner much exposure. Always strive to improve
Remember that there is a Hierarchy and I would not focus on a level at this point. His level will make itself known as he grows and matures. By that I mean The Bid Dogs will find you if you meet what they are looking for. It is hard for a standout not to stand out. The other levels are not looking seriously at anybody until Jr or summer before Sr. year and even into Sr. year.
Now is the time to work on Grades. The Better Grades the more choices and for nearly all schools the more $$ in total merit they can give. GPA/ACT/SAT means $$, I found that especially with NAIA where my boys were most recruited. By the time he hits Sr year it will be too late to boost the GPA much. Many of us spend a lot of money on the the athletic side but fail to put money into the academic side and the difference between a 2.0, 3.0, 3.5 and 3.75+ GPA could mean the difference between $0 and a $50k+ in merit aid. Check the school's scholarship page in addition to the roster size
Most important have fun, make this a positive, supportive and encouraging time time for you and your son. Once in college you will not have this time together dedicated to a common goal again. Heck, you may be lucky if he returns a text or answers a phone call from you after he leaves.