Yes. It's far fetched. Sony would not want to run the risk of confusing the average movie goer as to who creates the Spider Man brand of films. They bought the rights for a reason and that is to profit on it's name sake. Not somebody else. Film characters don't work like hip hop artists appearing on each other's records. Not only that, but how do you even begin to price something like that out? If you've got Spiderman in the movie, it could potentially draw even more people out to it than before, given his A-list nature. Again, that to Sony is worth a ton of money.
The only way you'd ever see something like that happening are if Sony and Disney teamed up. Not a chance that's ever going to happen. That's too many "suits" trying to come together to decide how their franchises are treated. Marvel Films with Disney have the kind of overseeing power that they don't have with Sony.
