That's a starting point. To be honest, most SERIOUS Ivy hopefuls parents who know what they're doing would look at the list of accomplishments and say "well isn't that cute." However, it's obviously all super impressive for a kid his age, and shows that if he really gets serious about Harvard/Stanford, he might do it. If he doesn't bump up against his limit, he at least he has the raw tools and mentality to maybe do it. Especially with the baseball side of it.
And just to be clear...I hate all that serious Harvard/Stanford parent thing...I would literally NEVER do that to my kids, it's total nonsense. There's letting your kids pursue their dreams, and there's joining in and making it your dream too, which so many of these parents do. What your kid has already shown is phenomenal, top 2% type stuff...he's going to do awesome. The important thing I guess is to let them pursue it within their interests, but also make sure they never feel like a full ride at Duke is some kind of crushing disappointment or failure.
GBR makes a good point about IB being more similar to a college diploma, with well rounded course requirements to complete for the diploma etc. That is a good prep for college, where you have to do the same sort of thing...that was definitely foreign to my daughter when she got to college and had to start tracking that stuff.
But AP classes keep you away from the riff raff too, as long as the high school offers most/all of them. Kids can basically take virtually all AP classes from sophomore year on if they're offered. They might have gym or health, etc, but otherwise they're going to be in classes with like minded kids just like IB. But if the school only offers 5-6 APs, then no, I would forget about it. One of the best things about APs is exactly that, the classes aren't bogged down with the dullards, so you want to be able to take most of your classes in AP if you're really trying to separate.
But AP doesn't simulate college the way IB does.
That said, your kid is going to crush it either way...I think you're putting a little too much stress on this. You shouldn't be worried that he's somehow not going to be prepared to handle college if he picks the wrong one. At Harvard, having IB vs 18 APs is just like a starting point anyway. It's not going to factor in the decision competitively in the least, it's just going to get you in the stack to actually be looked at.
Congrats on having such an awesome kid.