Ok. Have a coffee and no hangover. Hooray!
Our DS showed a talent for all ball sports from about 6. His passion was for football so that's the one he mainly did, but he also played a lot of cricket in the summer. At his prep school, like your ds, he was a natural selection for all the a teams. But although his prep school liked a sporty reputation, it wasn't actually much help for us with progressing outside of school.
We took it upon ourselves to find out when here were district football and cricket trials and took him along to them. He was selected for both teams so played for a couple of years in both sports. His district football coach put him in for trials with a professional club and they signed him at aged 11. At that stage he dropped the cricket because it was becoming too time consuming to do both.
I think rugby has the same sort of system too.
At 13 he got a sports scholarship to senior school because he was playing at a high level, but tbh that all became a bit of a pain, as the school understandably wanted him to play for them but he needed to play for the club, as he wanted to become a professional footballer, so it all clashed a bit uncomfortably and became more trouble than it was worth.
If your DS is year 4 I think it's good he is enjoying experiencing a few sports. He'll probably decide himself what he is more passionate about. But to take it to a different level, look into it all yourself.
One of my other DSes is at a school where they do give out a fair amount of sports scholarships if you are a good prep school player, but haven't taken it to a higher level, and i suppose they see potential. So I think it really does depend on the school.
Hope that helps.