Not necessarily, it is possible to just keep things quiet you know. They made a very public announcement that they were ending the DCEU. If they kept quiet until now then fans would still be invested in this and watch it. Its not like the new Superman has been filming yet, it would have been very possible to keep this info under wraps for a few more months. Even if people knew there was a new Superman that doesn't mean the rest of the DCEU was going to collapse.