Question are you going to reference Alan Turing anywhere in this DLC.
It would be nice
I'm sure it will be a Decision/Event for the UK. Bletchley/Turing was so absolutely game changing, you simply can't make it as part of the base mechanics that GER/USA/SOV have access to. However, its effects shouldn't last until after '45, when the rest of the world caught up.
The UBoat mechanics still aren't balanced. As a human, I find it a PITA (using EAI with excellent production scripts) to deal with as the Allies. It should certainly be available by '42 to help turn the tide in regards to Naval/UBoat Intel. As well, it should help against D-Day because while the phantom armies is an interesting feature, I don't think it will be able to properly reproduce Operation Quicksilver).
But this all comes down to how they are changing Invasion mechanics with Intel. Will they remove the silly "warning, naval invasion" which I don't think has any intel basis whatsoever? (even worse, it doesn't update you when the enemy invasion has launched from their source ports, as the AI will be forever planning invasions but many times won't have the troops or naval superiority to launch). Or will invasion warnings be done properly, ALL based on Intel. And will the AI plan invasions with ENOUGH troops to do the job, based on its Intel....and will the AI rush defenders/Navy to places where it believes the Invasions are going to happen?