In the futur Justice League #75
“A new Dark Army made up of the DCU’s greatest villains has formed on the edges of the Multiverse and the best and most powerful heroes are pulled together in an epic war to push the darkness back. In the end, the Justice League are killed by the Dark Army with only one survivor to warn the remaining heroes of Earth about what is coming for them!”
The writer Joshua Williamson said he was very serious about killing off the team.
"It’s an interesting opportunity to do this on the 30th anniversary of ‘The Death of Superman,’ which happened in Superman #75. We get to take Justice League #75 and do ‘Death of the Justice League.’
“We want people to understand, this is serious and this is gonna have a major impact in the DCU moving forward,”
But don't worry, it's just a few months vacation from horrible writers
“But then three months later, there’s still not gonna be a Justice League comic. It’s gonna be a while, and that’s gonna be a major part of what the DCU looks like after this story: There is no Justice League.”