In general, not so many Napoli players are in the world cup, so the potential for Napoli to continue to win in the second half of the season is clearly very wide open because Napoli can still formulate their best strategy to win games in the second half of the season. And also Napoli can improve their performances in the Champions League because the Napoli coach knows how the condition of their players is at the moment and also sees the opposing team's consistency starting to decline.
It is an advantage for Napoli if most of the players don't join the world cup, the players can get enough time to take a rest before the next matches begin.