Sony owns the IP and Ready At Dawn can not make a sequel without permission.
"As for The Order, it was absolutely the company's desire to own it. We love that game and we are proud of it. Unfortunately, we were at a point in the company's evolution where owning that IP was not possible. We hope to not find ourselves in that position again."
http://www.gamesindustry.biz/articles/2015-06-05-blizzards-paul-sams-joins-ready-at-dawn-as-new-ceo
"We have enjoyed a long and mutually beneficial relationship with Sony. They are a great company with whom we have shared many successes over the years. As a result, it is hard to imagine not seeing our future games on one or more of the Sony platforms. At the same time, we have worked very hard to make sure that our engine and technology suite is multiplatform."
http://www.gameinformer.com/b/features/archive/2015/06/08/the-order-1886-developer-ready-at-dawn-expanding-in-new-directions.aspx
