Hiya. I'm admittedly a very young adult, but I'm almost 20 and have had Crohn's since just before my 9th birthday (my 11th Crohn's-iversary is this month!). Honestly, I think it's better to have the disease surface in childhood than any other time of life. I learned to deal with it just as I was learning to deal with all the other 'growing up' things - school, friends, puberty, trying to find my place in the world - and it's very much a part of me, one that I think has made me more resilient, considerate, and more determined to do some good in the world.
In terms of treatment, I've followed the standard treatment regimen pretty much - 5-ASAs first, which worked for a few years, until I had surgery to remove a stricture before it became a problem. This was when I was 11, and it was actually a fantastic decision, because it put me in remission at a critical time, so I was able to put weight on, grow, and go through puberty without any of it being delayed. This didn't last, though, and I ended up flaring again on and off for most of my teenagerhood (thiopurines worked, but not well enough), and I'm still flaring now.
The rate at which companies are competing with each other and developing new drugs for IBD is much more promising today than it was even 10 years ago. So don't be afraid of escalating treatment if it seems like a more aggressive approach is needed, because the alternative is letting a flare progress and that's never ideal! I fell into that trap in my teenhood, and now I'm suffering for it, when I should be having the time of my life at university and not thinking about my Crohn's constantly.
In short: don't panic, and try not to think too far ahead. The future is so vast and unpredictable - when I was diagnosed, I never would have believed the scale of drug development and research that's going on currently. Take each day as it comes because trying to account for every possible future will leave you sick with anxiety. I hope for the best for you and your son, and do let me know if you have any specific questions!