Having a "Rest Of Europe" and "Under-23" team cheapens my enjoyment of an international best on best tournament, something that I have fond memories of dating back to World Cup '96.
The Team Europe idea makes no sense. Wouldn't the NHL want to showcase the considerable progress that nations like Switzerland, Denmark, Norway, Slovenia, etc. have made in producing world-class talent? I would've greatly enjoyed an expanded World Cup field, and any concerns about competitive balance could've been addressed with qualifying games.
Team "Young Guns" makes even less sense. I get that the NHL wants to showcase young talent, but why not just have a rule that requires you include a minimum number of players born in 1993 and later?
It'll be great hockey, but it's a bunk format IMO. Sorry, you're not going to convince me otherwise.