It really all depends on how well the books do. If it reaches the popularity of the originals, I could see them greenlighting a new season or OVAs. But it does raise the question whether they'd go back to Holo or jump straight into Myuri. I don't know how well the books are selling, but since he's made several that's a good sign.
Also, I don't know which studio holds the rights or if they'd sign to a new one, so we might also start over from the beginning, instead of getting Season 3.