I think some of you are jumping the gun a little bit. First, there's no guarantee that even with Sony in trouble they will want to hand any of the rights back to Marvel. Second there's no guarantee Marvel will have the room in Civil War or Phase 3 for that matter for Spider-Man, their plans seem pretty much locked for the next 5 years and having to co-produce something with Sony is a headache they're probably not going to want. If Marvel gets Spider-Man back the more likely possibility is that he would launch Phase 4, which means no Spider-Man films for at least 5 years. With many of the actors coming off contract after Infinity War it makes a lot more sense to have a big name property launching Phase 4 in case there are no further Iron Man, Thor or Cap movies.