Ok, so I've watched quite a few interviews and Feige pitched it as "on lease" to Marvel/Disney when Pascal asked him for help AFTER ASM2.. Pascal threw the sandwich at him and threw him out, but common sense came to her. So I am assuming that is what the structure is. From what I remember Sony bank rolls the whole thing, markets the thing, but Marvel has the creative control cause they are "leasing" the character(s).
Now Spider-Man was "on loan" from Sony for CW, IW, EG, but notice that no other "Spider-Man universe" characters were used. Those are all the Spidey villains, Black Cat, Spider-Girl, Morbius, Venom, etc. No one has revealed a list and there is specific language to these characters. James Gunn said he wrote Vol. 2 around Ego, but he didn't know and maybe some others in the know DIDN'T know that Ego wasn't fully Marvel. They had to do a trade to Fox? to get the full rights to him. Complicated stuff that I tried to uncomplicate, but seems impossible until Disney gets them all under their umbrella.
I think Hulk is still under a Paramount distribution deal, hence no Hulk movie. There was something to Namor too, but I never heard any confirmation. Feige and some others don't care to reveal that stuff. I give kudos to the media people trying to figure that stuff out. No confirmation of this, but I'm sure there is zero coincidence to Marvel offing Quicksilver and then Fox exclusively using him while SW was exclusive to Marvel after AOU. I try to keep up with all this stuff as much as I can.