It may not last forever, but right now superheroes have never been hotter. There are still a number of superhero films in development, and 2015 will be a crucial year with Avengers: Age of Ultron, and Batman Vs Superman, which has a long way to go to prove itself with the fans.
Being that Spidey is a Marvel character, an Avengers crossover would be irresistible, but he remains a separate entity from the deal Marvel made with Disney. When the rights for Spider-Man finally untangled over a decade ago, it gave Sony a rights deal that they can use any character or villain in the Spider-Man universe, but Disney would have to be involved in merchandising because they now own Marvel.
There has been speculation a Sinister Six movie could one day become a reality, and that would be an interesting twist on the superhero team formula, much like Guillermo Del Toro is working on a darker spin on the Avengers with Swamp Thing, The Demon, Constantine, and more.
There are currently two more Spider-Man flicks on the docket to be made, The Amazing Spider-Man 3, which has a June 10, 2016 release date, and Part 4, which has a May 4, 2018 release date. While Sony is mum about who could have a spinoff movie, Collider feels the Black Cat, and fan favorite Venom, would be good bets.