Brainiac on the big screen would be really interesting
I think that Brainiac has always been there, right under our nose, and both BvS as well as ZSJL confirmed it.
Superman Scout Ship is an
organic computer who possesses the science, knowledge and history of 100,000 worlds, enhanced the already exceptional-genius tier Lex Luthor's vast intellectual capabilities into those of a full-fledged supergenius-- as well as adopting the head-shaved cut as his new trademark card (Brainiac is bald) , can somehow foresee the future and is
profoundly afraid of both Darkseid, Doomsday, the prospect of an apocalyptic future and Dark Superman.
What else do we need to get that the Fortress of Solitude is the Living Machine? A sabotaged not-so-prequel-but-intented-to TV adaptation to
Man of Steel featuring a time-travelling Brainiac trying to collect Krypton and kill Superman's grandfather?
There has some iterations of DC Comics mainstream storyline where Brainiac winded up being reduced to the state of a organic planetary computing system by Kryptonians aeons before the days of Jor-El and the Doom of Krypton. I think that Snyder gets inspired by it.
EDIT: Remember the biomechano-nanotechnologic tentacles seen in the Scout Ship while the creation of the New Doomsday in BvS?