Hmm does seem a bit odd when you consider this was one of the the smallest sub campaigns in WW2.. and that its already been 'unofficially' covered in SH3.... (*
cough, GWX, cough!*)
Playable Japanese / British boats or Destroyer command or even just an import of SH3/atlantic campaign would have been more welcome.
The IXD2 will be lifted straight out of SH3 for sure (they'll probably just reskin it)
It sounds a bit 'El cheapo' if you ask me, I dont mean that in a nasty way, just pointing out its not a major project with significant budget, -more like a mini addon, I imagine a skeleton crew from the SHIV team will be producing it.
Still - I wasnt excpecting ANY expansion at all for SHIV - so better than nothing.

and at least they didnt hand it over to X1...
I guess they didnt what the 'Ubisoft riots of 2007' to go down in the history books.