I like to think that the discussions about the odds of playing at the next level do two things:
First they do add a little reality. I have a ninth grader who is just starting to really think about baseball beyond high school. We were on our way to a work out the other day and he ask me; "Whats my plan B?" Well, I know when I was 14, I did not even have a plan A, never mind a plan B. But it shows he understands that there is the possibility he does not make the cut at some point.
Second, it makes those kids with the desire realize how hard they need to work. My son, like many talented players never had to work that hard at the younger ages. He always practiced hard, because he loved being there. But he never worried about be good enough. Over the past year, he has been fortunate enough to play in some top national events and see the skills of the players around him. He also has had the chance to talk with some coaches and pro players and hear from them, what it takes. Some kids will then decide they just don't have the skill and/or desire to work that hard. Others will take it as a challenge and it will push them like they need to be pushed. I am sure all of us on this board hope our sons are the ones who take the challenge. (And have the skills to go with it.)