Always continue to stay in touch. Just as your son's process is ongoing, so is the school's. Maybe they're not terribly interested today, but next week, when their first choice doesn't get admitted or gets hurt or any one of a million things, you want to be the first person on their backup list.
These coaches are experts at playing the recruiting game. They will always be enthusiastic in front of you because they want to keep your son on their string just in case they need him. This is a business for those coaches, it needs to be for your son as well.