I kind of hope the NHL teams do not release their players. Isn't the plan to aim for a Jan. 01 start to the season? If that's the case there will be overlap and I doubt the NHL teams would want their players missing the start of the season for a junior tourney. Even if the NHL season gets pushed back, I'd still rather players like Dach, Lafrenierre, and Hughes held out. Those players would be playing in the NHL as we speak if not for the pandemic. They have already graduated from the junior ranks - I see no developmental benefit for them to go back and dominate. I'd rather the opportunity be given to actual junior players.
If those players are sent to the WJC, it won't be for developmental purposes. Teams would surely send them there so they can get to play some games.
Obviously closer to the WJC we get, the better idea the NHL will have if they can meet the January 1st start date or if it will be pushed back some more.
If the NHL does come back January 1st, then NHL teams will be having their camps during the WJC. So chances are Hughes, Turcotte, and other junior eligible players in the NHL will most likely be with their teams.