Kingpin is out of question, he belongs to Fox atm, they have I think at least three more years to make a DD films before the rights revert back to Marvel if i'm correct.
A lot of people want A LOT of stuff in the sequel. I remember what Mathew Vaughn said about the sequel to First Class saying he would only add one new character and i like that approach to ASM2. Keep it simple. No need to overload the film and then have so many new characters.
Stuff like Daily Bugle/JJJ is cool. But bringing in MJ, JJJ, Eddie, Kingpin, Norman, Harry... thats WAY overloaded.
1.Since two characters are dead and one villain is defeated,that gives us two characters too add and a third who will be the villain without over crowding the movie.
JJJ can replace Captain Stacy,and Harry Osborn can replace Uncle Ben's character while Norman Osborn is the Green Goblin as the villain.
2.Have Green Goblin kill Gwen.
3.Show Kingpin in a small minor role like how Dr.Ratha had in the first movie,and show him getting tired of spider-man ruining his business,and the Kingpin wants him dead.
4.Show how Norman Osborn was gonna make Kingpin some super villains,but he never gets the chance,because he gets killed.
5.Show Kingpin at the end of the movie talking to Harry about Norman's original plans too create super villains too kill spider-man.Now Harry and Kingpin want the same thing.
Avi Arad said they can use Kingpin if they want too in a recent interview.
SECOND FILM:
- Introduce the Osbornes.
- Spider-slayers.
- Scorpion (as an experiment by Norman and co) - main villain.
- JJJ.
THIRD FILM-
- Green Goblin
- Death of Gwen
KISS principle - Keep It Simple Stupid.