The World's Finest provided the first real concrete piece of information about the series, a Twitter response from Cartoon Network Canada acknowledging that a series will debut their but not until the fall of 2016. This makes real sense considering the calendar placement of Warner Brothers Batman v Superman: Dawn of Justice and first Justice League motion picture.
The rumors began when a photo appeared online that was taken at the Warner Brothers Animation department showing posters for a number of animated projects that appeared to be up and coming productions. An insider at the studio implied that the JLA title was short for "Justice League: Action" rather than the familiar Justice League of America. At this time there is no other information available, although the silhouettes on the poster do give some clues as to the roster for the series.
Source: World's Finest