Losing the CHL would be a disaster for Canadian hockey. CIS doesn't make sense as a development league, athletes have to go through too many hurdles to pretend like they're also getting an education.
Losing the CHL would be catastrophic for hockey in general.
Sweden, Russia and even the US have created junior leagues to try and emulate the CHL in a capacity for a good reason. 99% of kids under 20 have no place playing against men. 16-17 year olds benefit from making their way and the 19-20 year olds gain experience as go to guys and leaders among their peers which isn't always an option for players going into European pro leagues or NCAA.
CHL is better for the guys who don't have a future in hockey as well. They can play hockey and get their paid education for AFTER hockey instead of the ruse that is collegiate sports in America. At least CHL grads don't have to work a full time job while studying to maintain a certain GPA just to stick around. Canadian Law wouldn't even allow the CIS to behave in the same manor so the whole idea is moot (thankfully).
NCAA is a great route for a lot of guys who are going to take a longer route for different reasons but the best players will and should go the CHL route. That's considered a pro league for a reason and prepares players for a career in hockey as evidence by the thousands of players who've gone that route and made it (including about 80% of HHOF members). Saying Euros are ruined by the CHL is a completely unfounded claim. It certainly didn't hurt Lindberg or Prokarov or Landeskog or Hossa.
The only draw back of the CHL and it's agreement with the NHL is that occasionally you'll get a 19yo player who'd be better served in the AHL than with his junior team but those cases few and far between. No 19 year old will be hurt by playing another year in junior. Keeping the level of play up in the CHL is as important to the NHL as it is to each individual junior league. It keeps it far and away the most competitive environment for aspiring pro hockey players.