Real stats wrote:
The LR community is the least fact based group of so called runners that I have seen (not actually seen). Whether it is academics, running improvement, recruiting stats, or employment, nobody here seems to want to base their opinions on facts. Every kid that writes in and asks about their possible improvement, is given some anecdotal evidence of significant improvement. Yes, 1-1000 kids will improve by a minute through HS but if the average is 17 seconds, that is the most likely for each poster who is asking. It also means that for every kid who improves by 34 seconds, there is probably one who makes no improvement.
Milesplit just published a list of what looks like the fastest 400+ 2017 Freshman XC times and their improvement through yesterday (early senior year):https://www.milesplit.com/articles/266900-class-of-2020-freshman-to-senior-year-5k-improvement
It shows that about half of them dropped their times by 30+ seconds by the beginning of senior year, even with the ceiling effect that comes from having chosen only the fastest freshman to study. More than 50 of them dropped a minute or more. So all else equal, the OP's son has roughly a 1 in 10 chance of meeting his goal. If you assume that he is more committed that the average kid (as the title of the thread implies), and that he will have the best coaching that money can buy, I might give him a 50-50 chance.