I would assume an offer is coming. I don't think they'd be inviting your son up for an overnight to make a new friend. It's a big waste of your time, their time, and their hosting players' time, but it has happened where the whole thing is a bust.
You can't really push the where do I stand question unless you have a leg to stand on aka other offers you would be willing to take. What your son needs is an offer from a school he would be comfortable attending and he needs to be calling these coaches and letting them know "Hey coach I have an offer from another school. It's a great opportunity and they'd like me to make a decision soon, but I'd still love to come play for you at ________. I wanted to reach out and see where we're at before I commit elsewhere." You'll get an honest answer, good or bad. But I would say that applications are due in less than two months and fall ball probably ends in a little over a month. If coaches are calling your son nice and telling them they'd love to see him at a camp but not asking for grades or scheduling visits asap then they're probably not too interested. Or likely have his position filled.