I don't think it'll be that complicated.
The Kaiju stuff can be ignored. It'll be early on, as a means of establishing Superman's power.
The core of the plot will centre around accountability and Superman. Best guess is Superman intervenes on the wrong side of a foreign war (there are references to Boravia invading someone in the trailer + the scene with the flag). Maybe something goes wrong and Superman is blamed, bringing him into disrepute. But, ultimately, nobody can hold him to account as he is too powerful.
Lex unleashes "Ultraman" (Bizarro) to reign Superman in.
I'm curious as to Mister Terrific's role, as he apparently has the largest role of the supporting cast. It looks like he, Guy Gardner and Hawk Girl are in the employ of Stagg Industries. So maybe Mister Terrific is the one who rebels and works to uncover the truth?
And there's basically nothing to go on regarding Metamorpho in the trailer.
