The end of The Amazing Spider-Man 2 will introduce characters for the planned Sinister Six movie, according to a cover story in Entertainment Weekly.  Sony and Marvel announced plans for Sinister Six and Venom movies as an expansion of the Spider-Man film universe being developed by Sony back in December (see "Venom, Sinister Six Movies"). 

The Amazing Spider-Man 3 is already slated for June 10, 2016, and the Sinister Six will presumably follow. 

The Amazing Spider-Man 2 opens May 2nd; the final trailer was released last week (see "Final 'Amazing Spider-Man 2' Trailer").