Re: Spiderman in the Avengers "world"?
My personal feeling has always been that while I think he has no place on the Avengers team, Spider-Man will be sorely missed when / if Marvel adapts crossover arcs like the Infinity Gauntlet and Civil War. Same goes for the Fantastic 4 and the X-Men.
MCU Rest of Decade prediction:
2015: Avengers: Age of Ultron, Ant-Man
2016: Captain America 3, Doctor Strange
2017: Thor 3, Guardians of the Galaxy 2, Inhumans
2018: Avengers 3, Black Panther, Incredible Hulk 2
2019: Iron Man 4, Doctor Strange 2, Ms. Marvel