The first book, Black Wolves, was a semi-sequel to Elliott's earlier Crossroads trilogy, set in the same world. The second book, Dead Empire, was half-finished and cover art already prepared when the publisher made the decision to drop the series.
The news is somewhat confusing, as Orbit in the UK and Commonwealth territories has been Elliott's publishers for over twenty years. They released the Crown of Stars, Crossroads and Spiritwalker series, all of which sold well for them. Assuming that the reason for dropping the new series was poor sales, you'd assume that they would give the series more of a chance to prove itself, given the author's form and the sad but inarguable fact that many modern fantasy readers are now waiting until series are complete before reading them.
You won't be seeing this in the shops any time soon.
Hopefully it won't take as long as that before we series this series concluded. Meanwhile, Elliott is working on a new SF series for Tor Books, The Sun Chronicles, which she has described as "Alexander the Great in space" with a female lead. The first book, The Unconquerable Sun, will be published in July 2020.