When Warner Bros first announced that "Man of Steel 2" was going to introduce Batman and pave the way for a Justice League two-part movie, the move looked like the fastest way to catch up with Marvel's strategy of moving in Phases. Now, the idea of featuring superhero teams without stopping for individual origin films looks like a full-on strategy for how to make the most of the DC properties.
Will Smith, who recently wrapped his part as Deadshot in David Ayer's "Suicide Squad," is psyched about being part of a massive superhero cinematic universe.
Since he signed on for multiple appearances as Deadshot, the rumble behind the scenes is that he wants to be an ongoing part of Warner's and DC's plans.
Right now as per my sources IF things pan out Will Smith may join Ben Affleck in his solo Batman movie, which might not end up being so solo. If Deadshot joins the Bat in the movie, it will be for a "major role" for a "The Good, The Bad, and The Ugly" scenario.
Nothing's locked down completely, but most of the involved parties seem enthusiastic. Getting Deadshot and Batman to join forces in a movie isn't nearly as hard as landing two A-list actors like Smith and Affleck in one movie (that Affleck will likely direct), and could be another Batman V Superman sized event instead of just another entry into the canon of Batman films.
Batman and Deadshot teamed up in the comics as recently as this year's Batman: Arkham Knight comics (starting with issue 23).