I still have a tough time thinking top end players will avoid signing a pro contract and all the perks, preseason games, training, get to FA earlier, etc that Congress with it vs play NCAA. I also think we are also on the verge of seeing underaged CHL players granted the ability to play in the AHL as well.
Now mid round players, sure. I can see some of them jumping college, especially if their NHL team doesn't have immediate plans to sign them.
This may be the case, but until that day comes the reality is still that a player who has already played at a dominant level in the CHL at 18 is probably better off competing against older players in the NCAA if he doesn't make his NHL club than returning to play with his prey in the CHL. One recent example of this was Brandt Clarke, who was not challenged at all in the CHL in his age 19 season, and it certainly did cause damage to his development and his readiness to play in the NHL at 20.
NHL GM's have complained for years about this very situation, that they have to send 19 year olds who are very close to being NHL'ers back to a level they have already passed, this provides something of a bridge to that situation.
I also think you overrate the pre-season games stuff and some of those perks. We have seen countless college players who played no NHL pre-season games jump right into the NHL and not miss a beat (Luke & Quinn Hughes, Makar, Caufield, Knies, Faber, Beniers, Leonard), many of these guys jumping right into teams gearing up for the playoffs.
As far as contract, a player who plays two years of junior actually has his contract start a year later than the same player who plays two years of college and immediately signs (Luke Hughes and Brandt Clarke would be an example of this), and financially it's worse off because you sign the 2nd contract a year later. I am unaware of the CBA rules with regards to CHL players who would switch to the NCAA, my belief is they are locked into the CHL player status as far as contracts, but at best that would be a push as to when you get the 2nd contract (when real money begins). And also, while we aren't talking Bryce Underwood type NIL money, a top-end 1st round caliber talent is going to make some NIL money from the hockey programs with deep pocketed boosters, and again we aren't talking football/basketball, but there are some wealthy hockey fans who are going to support their alma mater's programs financially.