Three villains will be appearing in The Amazing Spiderman 2(terrible movie title BTW), some have said that it's too many, but I think that it can work. Here's how I think it's gonna go.
Rhino
Rhino will appear at the beginning of the film as regular thug that Spiderman catches, we have seen those pics. He won't appear again till towards the end of the film in his Rhino armor(which for some reason has to look like Transformer instead of just looking like Ultimate universe Rhino). He will attack Spiderman, thus Giving The Goblin time to snatch Gwen, who Spidey is trying to get safety(more on that later). He won't, however, be big opponent and Spiderman defeats him easily with some out-smart-plan.
Electro
Electro will be the true main villain of this film. He will attack Spiderman with full power and hate. He will be the one whom with Spidey has the big final battle of the film. And ultimately he ends up being the one who kills Gwen; when it seems that Spidey has saved Gwen, he will swoop up somwhere trying to give Spidey one last full charge, and Gwen will be caught in crossfire.
Goblin
Harry Osborn will seemingly be Green Goblin in this film. Trailer shows that he is apparently working with his father Norman Osborn. Norman will manipulate Harry to take Goblin formula, and attac Peter. In order to get Peter into trap, where Electro is waiting ready to kill Spiderman, Harry kidnaps Gwen. They'll have battle, and Peter manages to save Gwen from the Goblin, however; Harry Osborn will die. He will fly to his own trap, his glider/suit will explode or something, but he will die. Norman will become the Goblin in future instalments; he only made Harry the Goblin because he needed a guinea pig for the Goblin-formula, now that he knows it works he will use it cure the disease that is killing him. He will turn into Green Goblin(hopefully one that looks more like the Ultimate Green Goblin), and he will be a part of the possible Sinister Six in future films.
So these are my speculations of upcoming film. Tell me if you liked them, if you didn't; relax, they are just fan's thoughts.