Break the transfer window and also the world cup will still have an effect on the team. Even though they are not part of the national team squad that represents their country for world cup. Example the physical and mental health of the players that will change when the league returns. This is something that the teams who are fighting for the championship need to be wary of. Changes in the formation of opposing players from the transfer window can make the opposing team better. So, Napoli must be careful and maintain the physical and mental players in order to continue to appear consistent after this break.
If we consider the resumption of the championship as a restart, then Napoli should not experience problems, since the first half of the championship is always successful for them. The problem is that it will be an "unusual" start of Serie A and different players will be in a completely different state after the break (those who rest will be retrained and those who play will be tired). Everyone will need an individual program to get back into Serie A games again. But I think Napoli's medical/therapeutic team can do it.