I think the big problem in figuring out whether the game will get a sequel is not so much dependent on its sales (as it will be niche), but more so on its cost. Of course, if the games sells way more than anyone could have expected, this is less of an issue.
That said, there are reasons to believe that this was an unusually costly game for its niche appeal. The transition from a PS3 Move game to a PS4 games indicates that it likely had a long development time. Secondly, it features a LOT of voice acting, some coming from famous people like Hayden Panettiere, which is really expensive. That said, the mo-cap of the game is not up to the standards of, say, Uncharted, and the animations are incredibly stiff, so that might have cut costs.
Edit: Of course, sequels and spin offs would be cheaper, because they wouldn't having the rocky development and engine changes.
