No matter how well received Marvel's small screen offerings have been (Daredevil was hailed as their best adaptation to date), it's become apparent in recent years that the worlds of the Agents of S.H.I.E.L.D. and The Defenders will not collide with that of The Avengers. That's despite the fact they take place within the same Marvel Cinematic Universe, but it can also be blamed on Marvel Television and Marvel Studios being very separate entities that don't work together in a very significant way.
During a recent convention appearance, Captain America: Civil War and Avengers: Infinity War star Anthony Mackie made it clear why these crossovers aren't going to happen. "Different universes, different worlds, different companies, different designs. Kevin Feige is very specific about how he wants the Marvel Universe to be seen in the film world. It wouldn’t work. It wouldn’t work at all."
While Mackie can't speak for Marvel, it very much sounds like he heard this direct from Kevin Feige and, as suspected, it really doesn't sound like the Marvel Studios President is interested in using characters he isn't involved with reimagining for live-action. That means The Defenders and Inhumans are out in the cold, a shame considering the potential they have for many upcoming Marvel movies. This was to be expected, though, and short of some huge surprises, it's unlikely to ever change!