I have mixed feelings about this. Some of the people at the Ubi forum are understandably upset that U-Boats are going to be modeled i/s of Japanese subs and/or several important American classes.
The implication that Japanese subs did not really have an impact on the war is strange, and slightly offensive IMO. The Japanese fought bravely under a faulty tactical doctrine, and I am sure the survivors of the "Juneau", "Wasp", and "Indianapolis" would have some pretty strong opinions of their own about the Japanese's effectiveness.
I do appreciate that they are still willing to provide support for the game at this late date, especially since many people consider simulations to be a money losing proposition.
My main hope is that by concentrating on the most important aspects of porting over U-Boats and a Kriegsmarine career, the developers will enable modders from "Atlantic Sharks" and maybe some people from the GWX team to create a fully functional U-Boat campaign using SH4. The main concerns would be adding more Atlantic shipping lanes (easy), porting AI vessels & aircraft (fairly easy), adding any U-Boats and weaponry not included in this upcoming add-on (hard) and making appropriate career/interface screens (fairly hard).