It seems, the more I read of the speculation around Superhero movies, the more I see a lack of further thinking, reflecting the here and now mentality of many fans. For instance, a large number of the articles I have seen lately, especially those related to rumors of Jesse Eisenberg's Lex Luthor being a part of the suicide squad movie, suggest the Luthor himself will be set as the villain of [Batman v. Superman: Dawn of Justice](movie:711870), and that he will end up in prison so that he can join the suicide squad on death row. Now as everyone has the right to speculate, I will concede that my idea of what is to come has as much basis as theirs, however, I feel that logically DC would not play all of their cards so quickly by throwing Lex out as a villain to start, especially enough so that he would be in prison already. Instead I feel that Luthor will remain a spectator in each of these films, but slowly enacting a larger plot that will carry through the Justice League movie and not come to fruition until the next solo Superman Movie.
Let us slow down though, examine this role I have laid out for Luthor in individual circumstances to give us an idea of the whole. Luthor is incredibly intelligent, and strategic, especially in terms of politics. In Batman v Superman, when Luthor was cast, the public opinion was immediately that this would mean Batman and Superman are going to end up teaming up to take him down. However, it makes no sense for Luthor to make his move in this film, nor for Snyder and co to throw this into the mixture when they already have a huge battle headlining. Batman v Superman should focus on just that, Batman and Superman battling, not just physically, but there should be discussion of the political ramifications of each existing, and we should really get a good picture of the world in which the Justice League is going to exist in this film. This will give the movie more of a political Drama theme in which Superheros are involved, rather than a Superhero movie with allusions to other genres. Luthor should be developed as a popular figure, we should see he is intelligent and breaking into the political world, especially mentioning it may be unwise to trust a "Superman". He should be seen by the world as a good guy though. Then we should get a glimpse, as has been suggested by an extra already, of his large plan to come (the extra says that Lex already has Kryptonite as well as Zod's Body, and we'll see this when Batman breaks into Lexcorp).
In the Suicide squad film, suggesting Luthor is in it, he should too play almost a cameo of a role, perhaps talking to Amanda Waller about project Cadmus and his interest in investing. Just one scene of him making such a suggestion will be all that the movie needs to link it back to the Justice League, while letting the film be its own. Think, just in saying that one line we know:
a.) Lex Luthor will be working alongside a government agency
b.) Waller is already taking precautions against these Superheros that we have seen rise up in MoS and BvS and
c.) Project Cadmus will play a role in future DC films
Now, in my opinion, Eisenberg should not even be revealed as a villain in the Justice League film. Either another villain (Braniac, Darkseid, etc.) should come to the Earth to unite the League, or Luthor (perhaps alongside Cadmus) should create Doomsday, but it won't be revealed yet. At this point, the League should be in the middle of the political spotlight, with the question even more prominent, can we trust these heroes? And Luthor will rise as well, to a high office on his way to the presidency.
This, I feel will relieve many of the qualms fans have based on his involvement in these films. It will keep BvS from seeming too crowded, as he will be a character of note, but not in the sense that a Villain usually is in a Superhero movie. It will make sense that Luthor is not in the Suicide Squad, because really? Why would Luthor be in the squad? Maybe to plan, but come on, this would be a demotion for him. It also gives us an idea of the hand DC is really playing, instead of seeing Superhero movies with villains popping up and disappearing after one film, we have an interwoven universe full of these heroes and their villains, who the writers can explore in depth as round, developed characters over years.