With Captain America: Civil War currently igniting the box office, many can barely contain themselves for the upcoming Avengers: Infinity War 2-Parter.
One of the most telling might be from Anthony Russo (co-director of Captain America: Civil War).
At the same time, if The Avengers remain as splintered as they are when Civil War ends, even The Defenders will be forced to pick sides.
Having characters like The Avengers and The Defenders crossover is difficult due to entities (other than Marvel) controlling certain characters.