Just putting this here for posterity:
Eisenberg as Luthor, a young, upstart, information age billionaire, up against Wayne’s “old money” industrial complex, Wayne Enterprises. This gives Luthor unprecedented access to the world’s advanced information technology and personal information, which is arguably hugely valuable to someone like Batman.
Following the events of Man of Steel, the worlds richest and most influential people meet as allies to discuss the new “Super-person Problem”, including Luthor and Wayne. Superman represents both an incredibly destructive force (see Metropolis and Smallville), but also a power that money can never buy. Both are dangerous things, they represent a lack of control by money/influence/etc. Wayne, as always, needs to know more so he meets Superman as Batman and changes his stance after a tense go between, ultimately trusting Clarks honest and sincere nature (this plays to Batman being smart and Superman being altruistic).
This prompts Luthor to double down on his efforts to “Protect Humanity” (he would probably need the support of Wayne Enterprises, who is now out) while secretly coveting the power of Superman. Luthor would probably have the full support of humanity and government (again, see Metropolis/Smallville) and could foster that support through his new media outlets. This pits Luthor both against Wayne and Superman by the 3rd act.
Add in things like Wayne investing in Luthor’s company pre-IPO and revealing a controlling stake to thwart Luthor on the money front (Wayne as a billionaire through experience, something Luthor lacks), Alfred being “pro-human” after seeing the destruction caused in Man of Steel mirror his experiences in war and Superman struggling with his isolation from the humanity he swore to protect (cueing Wonder Woman’s entrance) and you might have the start of a movie I might want to see.