year 1 (e g 2014) the Olympics, in February, NHL takes approx. a 20 days break.
12 teams, top 10 according to IIHF ranking directly qualified, 2 spots available for all other teams (qualification tournaments held in September).
year 2 (e g 2015) the World Championships, in May, NHL runs whole year without a break.
16 teams, 14 teams from previous World Champs directly qualified + best two teams from Division 1.
year 3 (e g 2016) the World Cup, held approx Dec 27 - Jan 10. NHL takes approx. a 20 days break.
10 teams, top 8 according to the IIHF world ranking, 2 spots available for all other teams who wish to qualify (qualification tournaments held in September).
This tournament is arranged by the NHL, all possible profits belong to the NHL and it will always be held in North America.
Btw: the WJC is held at the same time, somewhere in Europe - all U20 NHL players will be able to participate in their WJC tournament, since NHL will be on a break.
year 4 (e g 2017) the World Championships, in May, NHL runs whole year without a break.
16 teams, 14 teams from previous World Champs directly qualified + best two teams from Division 1.
after that, another 4-year cycle begins...
So, in summary: The World Championships, very similar to what we have know are held every 2nd year, lower divisions will have longer tournaments (two year tournaments to decide the division winners).
At least once in 4 years a best-on-best tournament will be held in Canada or USA. NHL has to take a (20 days) break every other year, but several months before the Stanley Cup playoffs begin.