From the Q and A:
Q&A video posted from the official Twitter account. Clears up some confusion about RPG systems/open world. Adj_noun's transcript is way better than mine, using that instead. Second Q&A added Transcript courtesy of Adj_noun yet again, thank you. 3rd Q&A
www.resetera.com
Can you play as any character at any time in single player, or will there be specific chapters tied to specific characters?
The character you're playing is based on the narrative. It's the best character to push that narrative forward. If you were to go through the story in a linear fashion, you will be playing as the story dictates.
However, you can still go off and do these tangents as your chosen character, whoever your favorite hero is, and level that hero up and do cool missions with that hero.
You can say, 'I don't want to play this mission, I don't want to play as Hulk, I want to play as Black Widow.' You can go off and play as Black Widow and learn and feel what it's like to be Widow in those missions. And then come back to the main narrative which dictates what you play as.