I don't have the rules in front of me, so I'm not sure how many troops the submersible is supposed to be able to carry (apparently that is its main function). If it's a low number (and I'm guessing it is, since DeepWars is a skirmish-level game), then I can see this being the right size. Maybe a *tad* small, but close enough.
Dakkar, I understand where you're coming from. The only reason, however, that I even know about DeepWars is because I saw the Ancients starter box set at Gamer's Haven a few years ago. I have no idea what their presence is in other stores, but I'd bet they don't have a whole lot of exposure. However, I think the Haven can order just about anything in their catalog, they just don't carry the products anymore (likely because there aren't very many players in the area).
But I think Antimatter Games is a pretty small company, so I don't see them really competing with GW, Privateer Press, CMON, etc for a slice of the 28mm market. As you said, they're in a niche.