Real or not I love this! Maybe is Scott's soul? He was a Phoenix host after all...
Also Guys look at this!
They reference Endsong again!! They say that Jean ascended to a Higher Plane of Existance!! This hypes me more for Ressurection! Also forgot to tell you that even Jean doesn't have the Phoenix she is the Phoenix. Like
Marvel said it:
The real Grey, having been raised from the dead once more, drove the flaming essence out of Emma and made peace with her permanent Phoenix union—now able to harness the power of the Phoenix even as it inhabited another host.