So all those stories of what the Japanese should have been doing with submarine warfare are going to now be done? Will there be a need for large numbers of NPCs to ship cargo across the Pacific to keep bases stockpiled, plus ships on the opposing side to try and torpedo them?
You can then get into the fun of playing the convoy escorts, dealing with an opponent who has unhackable comms (opposing U-boat force is using chat and Teamspeak instead of Purple or other Japanese codes to communicate).
So you could have a player who is an Admiral using their resources to set up a convoy to go across the Pacific to supply a base. Along the way there, he gets notified that Japanese subs have spotted the convoy and are attacking (and the attack is real-time). If that player belongs to a guild, they can notify their guild about the attack so others can jump into the convoy escorts to fight the Japanese, or if nobody is online the battle is played out with NPCs on the escorts vs PCs in the Japanese submarines