It'll be interesting to see how future changes between the CHL/AHL agreement affect the development pathway. If 18 and 19 year old CHLers were allowed to play in the AHL, I think that would stem the bleeding for the CHL. As it stands, the NCAA is a clear stepping stone between major junior, and pro hockey. The age difference is the primary factor that differentiates the NCAA from the CHL, and it does a really good job of providing top prospects with an environment to continue their development, face a new challenge, and a higher level of hockey, without having to take on the rigors of the NHL.
It's really disappointing from the perspective of a Canadian, and a CHL fan, to have talent flow into the US, but I think it's impossible to ignore the obvious appeal for these players.
Hopefully if players only play a single NCAA season, like McKenna, then when they are drafted, they are drafted out of the CHL, as well as the NCAA. When McKenna is called first overall at the NHL draft, it should not be the NCAA program that gets the credit at the draft podium, and the NCAA should not be taking credit for graduating X NHLers. The CHL should still be taking credit for the NHLers they graduate, regardless of whether they play their draft season in the NCAA, or not.