While the first Infinity War movie won't arrive until 2018, the Russos revealed quite a few details while discussing the aftermath of the Civil War. But, first of all, they once again reminded everybody that the movies start shooting in November, which means that the scripts must be done before then.
And that leads to another point: it will be one hell of a schedule for the actors who premiere their solo films during that timeframe. For example, Chadwick Boseman will shoot back to back Infinity War movies, plus the Black Panther movie. When will he find time for something else?
Back to the Russos…the directors also revealed that the movies will try to stick as closely as possible to the rules of physics established thus far. However, all of these rules (even if real) are just theoretical - since, you know, no one has ever fought in space – until now. So, a different approach is needed. Thus, this realism will be doubled by a psychological realism, to which the audiences can actually relate.
When the subject turned to Thanos, the directors once again said that he’ll be the villain to end the MCU’s problem with one-note baddies. When asked who will be able to take on the Mad Titan, as he is collecting the Infinity Stones and becoming more and more powerful, the directors said that Scarlet Witch hasn't even scratched the surface of her true potential, while Vision still has a lot to learn about his own powers (CBM).
We'd count Vision out, though, since it is very likely that he alone (powered by just one Infinity Stone) wouldn't stand a chance against a villain using multiple gems.
The Russos also teased the special relationship that exists between Scarlet Witch and Vision. In the MCU, they both receive their powers via an Infinity Stone - so a connection already exists. However, the directors also teased a romantic relationship, just like in the comics, during the Infinity War (CBM).
Lastly, the directors also revealed a special first Infinity War appearance by a certain superhero: Captain Marvel, who is set to make her solo debut in 2019, two months before the release of the second Infinity War. Obviously, they shouldn't have said that.
So, when asked to repeat the statement, they said that Captain Barvel will appear in the movie (CBM).