Only thing I could possibly think:
Silent Service III (but the SS series was only Pacific, and we just got ShIV, so...unlikely)
New Sonalysts sim (688i/Sub Command/DW successor...however, these games have done progressively worse in market each release, so...unlikely)
Red Storm Rising II (Cold War rather passe anymore, so...unlikely)
...and now for...
Aquanox (best guess, and heck,
it's already in development)