From the start of age 8 every program deals with kids coming and going whether they are cut, want more playing time, bad fit, grass is greener, ....etc. Mount and these other schools/programs are no different. There is constant change and turnover for whatever the individuals reasons are. These kids at some point need to learn to fight for their playing time because that is the nature of this sport. If you don't think your kid will be mature enough to live away then don't send him. But if you do think they are mature enough it is a great experience and they will for sure get better. It's hard not to when you play against the best every day in practice and in games even if your kid is a 4th liner.