Disney didn't buy out the rights from Fox Studios, they just went out and bought Fox Studios, so problem solved. They way I understand it is Sony got in on the ground floor, basically, Marvel didn't have a studio and was hurting for money and selling comics and toys was their main focus, so just sold them the rights, with in hindsight, are pretty laughable conditions. Sony paid $7 million and maintains the rights as long as they put out a Spiderman movie every few years.
One day Disney may buy out the rights, but how much would it take? That's a huge cash cow, Sony can put out a Spidey movie and make $1billion+ with every movie, so much would it take to pry that away? How aggressive does Disney want to get since they own the merchandise rights? They can just rake up the money up that falls off Sony's movie money tree. I'm sure there's a number that could make it happen, I certainly don't have enough fingers and toes to count what that would be.
As fans, it would be nice to see him in the MCU, but we're finally starting to see that already. It may be better that Sony keeps him, if Disney owned it outright, it's also possible we would see less of him with all the phases and other characters they are working on. At least with Sony, we're pretty much guaranteed to have a new Spidey movie every few years and that they finally realized the kind of cash and impact those movies can make, especially if they can maintain the quality. Who knows, Sony may even be able to entice James Cameron to make that Spidey movie he never got the chance to make. I'm sure
@DallasEast would love to see that!