Maybe its about Peter Parker's ghost? My first impression was,
A. Peter's ghost was a pretty similar blue as the smoke and text.
B. "Is He?" could be "Is he really dead?" or "Is he really gone?" because of Otto "defeating" him inside his own head
C. "Be Vigilant." Has Peter been appearing in the background of issues and we just haven't been vigilant enough? Or if he has not, will he, sometime soon??
That's just my theory. Any thoughts?