>>11548382
It isn't being delayed, they're saying Matt Reeves is still working on the script, which is code for them waiting to see how Superman did and whether they want to pursue a Justice League with them together or keep them separate. It's all about which path would make them the most money. The script, which is always mostly dictated by the studio anyway with which villains to use and which stories they want to adapt, is most likely finished and they're just making world building changes to link things together. WB also wants their new movies to shine and gain a following on their own before playing the Batman card.
Batman is the one character they have left they can make money with so they're super cautious about not letting it turn poison again like after Batman and Robin. That's why the Batgirl movie was disappeared.