My guess is it will be a d12 system similar to the one in Bulge. The mention of cruiser pieces will stir some conversation over at the Larry Harris forums in the Deluxe discussion.
My guesses go:
Hex based map
d12 Combat system with hits determined randomly.
Stacking limit of 12 units per hex.
Supply tokens that must be moved by ships.
Land units that must be moved by ships.
Reinforcement charts with new units each turn pre-determined.
Ships will take more than one hit.
Ships will be BBs, ACs, Des, Subs, Cruisers
Some sort of Marine Infantry unit.
You will have to build air bases or you will not be able to keep your aircraft in range of the battles.
I don’t have enough historical knowledge of the battle to guess the victory conditions.
They have announced it but it will be June probably or July even before they really start telling us about it. Probably mock ups will appear at GenCon.