To revive this project would be interesting as well as challenging.
However, you should keep in mind 2 important things:
1. It could be technically and enforced by the engine only for a timeframe to be covered up to a maximum in the early 1960èr
2. FORTS Ultimate should serve as a base for a variety of good reasons, so it would be an imaginable add-on for and with FortsU
Many basic requirements are already in place, such as really nice submarine models of the GUPPY conversions, overwater units can shoot torpedoes and many large units from the WWII were active even in the 60èr years in service.
From the fictional scenario, there are many opportunities for an escalation in the "Cold War" - I think only of Korea, Vietnam and Cuba ...
It would still be a lot of work to invest - the question is whether something would be desirable at all.
