They have already confirmed that TASM 2 will be Electro's film and a launch pad for the other villains. Through the viral website and cryptic interviews, it has been deduced that there will be a horde of villains in the Spider Man movies. What they have not confirmed is whether there will be spinoff films in between. Sony has already confirmed TASM up to the fourth movie, and targeted release dates until 2018. When they consider the box office success of the Marvel movies (The Avengers $1.5 billion, Iron Man 3 $1 billion and recent Thor: The Dark World about to reach $700 million), it's clear that Sony wants to emulate the Marvel model. Sony has the rights to Spider Man and they want to develop its own universe.
Marvel has the benefit (or burden, depending on how you look at it) of three different studios handling its characters. Anticipation continues to build for the Marvel character movies, and 'The Amazing Spiderman 2' is not about to lag behind.