I'm not a developer, and I don't even play one on TV but for what it's worth I don't think taking Silent Hunter past World War II would be a very good idea. While both the US and Soviet attack boats were very active during the Cold War there wasn't (thank God) any outright combat between subs so to have a viable campaign going you'd have to do hypotheticals. There are plenty of ways that a shooting war between NATO and the USSR could have happened during the Cold War but no matter which one you'd pick someone would claim that it wouldn't have worked out that way, or the war would have started over here not over there, etc.
So while it could be fun, there are problems with doing any hypothetical WWIII scenario. If you stuck to straight history then you'd spend your entire career shadowing Soviet warships, running ASW excercises, the occasional Tomahawk launch here and there, doing covert signals intercept missions and once in a while dropping off a SEAL team. Now while all that could be fun, it doesn't exactly scream Silent Hunter to me you know?
So if I had my druthers SH would stay in WWII. Now if you'd said something about WWI I could get behind that too because there was a lot of submarine warfare going on, not just U-boats, and it could be interesting. But the Silent Hunter name has always been associated with WWII and that's probably where it should stay.
Again, all of that is in my opinion, off the top of my head, gut reaction, etc.
