I dont think the ubisoft devs would consider WWI an era to make a uboatgame about, not after this:
http://www.subsim.com/radioroom/showthread.php?t=94508
http://www.shells-of-fury.de/
This game never got my juices flowing, but it was made on a much smaller budget than IE SHIII..But, there is always room for improvement, and with some advanced TLC to the graphics & some concern for the playability, i dont think its impossible..