Olympic games were only see as potential seriously taken competition for NHL and NHL players. World Cup, World Championship was based on minor or almost retired players and NHL rebelling if Olympic slot threatened their schedule of fast paced games. This time is over.
There is still big question about health insurance of some start players, that's why they withdraw from World Cup. Other players want their free time or were just insulted by previous rejections from national squad - Hudler, but majority of NHL stars is on World Cup rosters of their teams. Crosby is a captain of Team Canada, Ovechkin will shine for Team Russia.
There is other reason why NHL run open game in the winter for thousands of fans or World Cup - financial aspect and gain. They will get just $60 mil bucks income from World Cup, a half of this goes to the coffers of NHLPA. Not bad reason to say no to NHL players to be on the rosters.