Justice League: What Does The Ending Really Mean?
4. Darkseid Is Still Out There
At one point, Darkseid was going to play a huge part in Justice League. Tipped to be the main villain of the then two parter, the rumours coming through the grapevine have been that the classic DC antagonist was going to show up in the climax of the finished film to replace Steppenwolf, an idea which Joss Whedon eventually threw out.
Consequently, pretty much the entirety of the climactic fight was reshot (you can tell, because Supes' dodgy upper lip is in full effect), and Darkseid was virtually written out entirely. Still, his presence is felt throughout the movie, with Steppenwolf declaring that he's attempting to merge the motherboxes in honor of the villain to get back in his good graces.
Consequently, while he didn't show up in this movie, it's clear that Warner Bros. still have big plans for Darkseid going forward. Instead of rushing him into the finale of this flick, it's more likely that he's being set up for a future film in the same way Marvel teased Thanos as the big bad for years.
Even then though, he probably won't show up in Justice League 2, because...