While there are rumors implying the contrary, I'm told Sting has not agreed to a deal with WWE. We can, however, confirm there is strong interest from WWE as TNA Wrestling is also looking to re-sign him.
In fact, we reported here on WrestlingNewsWorld.com Premium on December 19, 2013 that re-signing the Stinger had become a priority in TNA. As almost everyone knows by now, Sting works on a year-to-year contract to keep his options open this late into his career.
There is also interest from the new promotion by Jeff Jarrett and Toby Keith. While there isn't much known about the new project, I've heard enough to report it has legs. The promotion has solid financial backing and aspirations of overtaking TNA as the number two mainstream wrestling promotion in the United States.
Back to Sting, there are people within WWE acting on "more of a hunch," feeling that a deal is imminent. However, there's nothing to report as of press time other than it's ultimately up to Sting as there is still interest across the board.