A new press statement,though not yet released,mentions Green Lantern will appear in Justice League after a Green Lantern sequel,as said here:
"Justice League is going to possibly be a continuation of our Green Lantern franchise,but will not feature Green Lantern on the team until after Green Lantern's sequel. If both of the movies are a success then the possibility if far greater,we are currently in discussion as of now."
So,his source appearently has not let him down yet,but I am a little sketchy,it being April Fools Day and all,but you never know........
other articles relating to the "undisclosed source" :
The Ant-Man(Black Panther,and Hawkeye) Cameo Article
Skrulls Will Not Appear in Avengers
Disney World/Marvel Movies