It seems like Sony retained ultimate creative control over Spider-Man in the deal in the first place. There probably is something in there, however, that Marvel gets a lion share of input on Spider-Man if he's involved in the cinematic universe. This likely explains why Sony is pushing out films tied to the character but set outside the cinematic universe. We're getting an animated property and a Venom movie. I just think it is a huge mistake to make a Venom movie without having a Spider-Man solo flick come out with him wearing the suit.
I think the logic behind Marvel's decision was quite simple: if Spider-Man is in future films, the popularity of the character can help mitigate the loss of Robert Downey Jr., when he retires after Infinity War (he'll have played the role for eleven years and been in more movies than Hugh Jackman had as Wolverine, not counting his cameo in First Class) and they can retire one wise-cracking genius for another more likable one. Sony only gets the profits of the solo Spider-Man films, which, if they continue to be good, only continue to drive his popularity upwards. Sony agreed because it brings in a popular franchise into their Spider-Man ones.
Sony doesn't have any of the merchandising rights for Spider-Man. They sold them along with the television rights a while back. I think Marvel made the smart business decision to try to play a hand in the most visible aspect of the property, the movies, to make more money on the merchandising rights, such as toys and video game licenses. If people become sick of Spider-Man as a character, that affects their bottom line as well. It is a win for Marvel as well (in addition to the movie related stuff listed above).Marvel is basically giving Sony free money just so they can use Spidey in avengers and just so Sony quits messing up their marque character,.
The real question is: will Spider-Man: Homecoming return Spider-Man's box office prowess to the near billion dollar club (adjusting for inflation) that the first and last Raimi movies did? At what point will Sony consider the movie to be a success? They wanted The Amazing Spider-Man 2 to make a billion dollars and it seemed it needed at least Spider-Man 3 level money in order to actually make money. It didn't. Of course, The Amazing Spider-Man 2 had a bloated budget of over $250 million and a marketing budget that was likely just as bloated.. Sony has shown a lot more restraint with their marketing strategy this time around. Perhaps they'll be okay with the modest success of the first The Amazing Spider-Man. My concern is what options Sony has to back out if they view the film to have under-performed. My hope is that there is little that can be done. Well, my actual hope is the film is good and it does well. But...still...On the surface it seems like a win win win win win for sony.
I also think that it seems like a win, win, win, win for Marvel as well. At least...so far. Again, it depends on what happens with the above. However, if this deal is rock-solid, which I hope it is, it seems like one of the best deals for both parties that have been made in Hollywood for years. Both sides come out, perhaps not mutually better off, but way better off than they were when they made the deal. It just shocks me that Fox seems unwilling to come to the table for discussions after this. But I guess they feel like they've come out properly ahead with Deadpool and Logan, which were two properties that were unlikely to be made within the confines of a cinematic universe like Marvel's.
I really doubt that Venom will be set in the cinematic universe if Feige isn't producing it. Given that he isn't, I have a feeling that the property is going to manipulated in a way to ensure that Venom exists without Spider-Man. At that point, though, it doesn't really seem like Venom. I really wish Sony would just make a movie of Silver Sable or Black Cat. If they make a Venom movie set outside the cinematic universe, Marvel will probably be reticent to use him, which is a shame because two of Spider-Man's best villains (Carnage and Venom) are symbiotes. I sincerely hope that this film gets canned or otherwise pushed back to 2019, after Marvel can exercise some input and get Spider-Man to have the suit first.