The writing first appeared on the wall when both series were unexpectedly pulled from the schedule last October (and by “unexpectedly,” I mean "not even the shows’ producers were informed of the change"), and continued today when Cartoon Network announced its traveling upfront presentation with neither series on its list of returning shows for 2013. But maybe there was some chance? After all, the blurb for the forthcoming Beware the Batman mentioned the DC Nation block! Alas, no. Green Lantern showrunner Giancarlo Volpe tweeted the following some hours following the Cartoon Network press release:
@solaana This time we knew.They just didn't want us to announce it publicly until they did.— Giancarlo Volpe (@Giancarlo_Volpe) January 28, 2013
According to Newsarama, Warner Bros. Animation has confirmed the axing of both shows, while Cartoon Network has only said that the episodes that have been completed will air.
While we're at it, it's worth noting that Star Wars: The Clone Wars was also missing from Cartoon Network's list of returning shows. Presumably, Disney’s purchase of Lucasfilm means the series will switch channels, should it continue. Series director Dave Filoni stated in Star Wars Insider 137 in October that scripts and designs for Season 6 were underway.