Great topic! This can be a seriously problematic issue in many ways. So many here say their son lives for baseball, is 24/7 baseball, etc. We talk about the commitment it takes... how a player has to be "all in", how college baseball is a full time job in itself and how a player must make sure he outworks his competition. We never want to stand between a boy and his dream (who then becomes the young man and his dream).
For the most part, the work ethic, the competitive drive, the team first attitude, the learning early to deal with difficult bosses, all the great life-lesson learning that the game brings about is very advantageous to future career endeavors. But i think for many, baseball does become such a huge piece of their identity, it can be a very difficult transition. Finding something else they love can be a task that seems highly improbable - how do you replace your childhood/young man's dream pursuit?
Then, as CoachB25 alluded, there are peripheral casualties. Years of structured, mandatory conditioning suddenly goes away. For some, a diet has been put in place that isn't appropriate for someone no longer engaged in daily regimented high intensity workouts. Many will initially celebrate "the end" by taking a lengthy break from that strict conditioning regimen. Some will not return to sufficient levels.
Preparation, regular communication and balance. Ongoing support, encouragement and celebration of who our kids are outside of the game, starting at an early age. Those are the keys, I think. But what are the answers for those who didn't know to do this as they were navigating parenthood with a serious athlete for the first time? I don't know the answers. For us, it was part dumb luck. The one kid that was the serious athlete also happened to have the opposite problem of too many other interests. Our battle was to get him to narrow his focus at times. But I see so many others who are/were 100% baseball from a young age into adulthood. I see some really struggle with this transition, with finding their new identity or realizing they always had other things to identify with.