As the mastermind, architect and producer of the Marvel Cinematic Universe, Kevin Feige is very much aware of every upcoming project/plan for the franchise. A committed leader and seasoned storyteller, Kevin Feige could easily land any job in the industry faster than Thanos can snap his fingers. But he loves the MCU too much and won't leave.
That's fine. Those movies need him. As for Marvel's TV arm... well, he isn't nearly as involved with that. In fact, he doesn't even really know if any of the Defenders or their friends will ever show up in an MCU film. As Kevin Feige recently when asked which of those particular Marvel heroes he'd like to see in a movie:
I don’t know. There were a lot of great characters that were on those Netflix series, and I think there is a period of time… it’ll be a while before we could use any of them based on what the contracts were, so I’m not sure. And also, even answering that question is a spoiler. But there are some great Marvel characters there.
Kevin Feige isn't remotely concerned about possible superhero fatigue, and the recent successes of Captain Marvel and Avengers: Endgame just give him even fewer reasons to fret. But for some, Marvel's street-level heroes were nice respites from the cosmic threats of their silver screen siblings. With Disney+ set to release this fall, it's unclear how these heroes and their cancelled shows will fit into the MCU. If they can at all.
They could guest star on one of the streaming service's planned limited series, but even Kevin Feige has no clue if we'll see these characters fight alongside the more traditional superheroes from the films. But for now, as is evident from his interview with BET, he's clearly dodging the question, but can you blame him?
Fans come up with some outrageous rumors and theories, so indirectly answering a super spoiler-y question is probably a wise move. And, quite frankly, Kevin Feige doesn't really have time to worry about heroes he hasn't worked with extensively. Sure, he's introducing new characters with each successive MCU outing, but that's his field house. Plus, he's probably had their appearances planned for years.
Kevin Feige already has so many characters and concepts to worry about that it's probably unwise to hope too desperately for a Defenders/Avengers team-up. Still, the notion is an attractive one. It's far-fetched, but attractive.
As a final side note, would the Defenders fit into the wilder, more whimsical world of the Avengers? I'm betting not, but who knows. They made a live-action Rocket Raccoon work, so I'll believe anything at this point.