The Animation Guild blog listed Justice League Action as a show being worked on back in August and recently a very reliable source relayed to me some information that confirms both the blog's information and the original Cartoon Network Canada tweet to World's Finest Online.
Justice League Action is already well into production and planned for a debut on Cartoon Network in the fall of 2016. Knowing how badly the network handled the DC Nation block and shows like Green Lantern: The Animated Series and Young Justice it's easy to view this information with a sense of apprehension. Hopefully the network will handle the show more like they did the previous Justice League animated series - and a lack of merchandising shouldn't sink the ship this time around. To be clear, though, this is an altogether new show and not a continuation of the previous one.
What does give me great hope about Justice League Action are the names of the creators and actors connected to the production. While I cannot reveal what I've been told I can say with confidence that the names I've heard thus far are not strangers to handling the characters and they have a great track record. We can expect to hear some very familiar voices in some familiar roles as well which I'm extremely excited about.
As for the Green Lantern universe - I'll just say that the emotional spectrum will be well represented!