I won't go into specific details of what I think will happen in
3 I'll just tell what I think the end results of the villains will be. Then what I think will happen for 4, 5, and 6.
3
Harry Osborn - I personally think he'll make it alive in this movie, and possibly make the 4th movie. Because while promoting FlyBoys, James said he would come back for a 4th movie if the cast was good, and if Sam was in it. Aparently hinting that Harry doesn't die in "3".
Sandman - I think he'll be bit by Venom, during the Final Battle.
Venom - I think in the Final Battle he'll put up a huge fight, then somehow at the end the symbiote will be seperated from him and Brock will be emprisoned.
SPIDER-MAN 4
Maybe Peter could turn into Man-Spider in this film, and need Connors help to be cured, but the problem will be that most of this film, Connors will be the Lizard, which makes it difficult to cure him.
Possibly they could show the plot of where Harry harasses Peter EVERY day, and have one battle at the very beginning of the movie. Then possibly have Harry lie low for a while.
Dr. Connors could be working on the limb regeneration formula, and finally get it, and becomes Lizard. And Peter, who is standing right beside him, is forced to fight Lizard in an intense battle.
Kraven is hired to fight Lizard, and the two of them fight, and Spidey steps in to try and protect Lizard from harm, which gets Spidey on Kraven's bad side. (Btw, perhapes Kraven could be a more contemperary version... i mean, he still use primitive weapons... he just could be clothed a bit more contemperary...
) After fighting Kraven, Peter can bring Lizard back to the lab (uncouncious) and temperarily cure him.
Maybe Aunt May could be discovered sick, and dying, and she's taken to the hospital.
Anyway, then Peter turns into Man-Spider, and goes out into the city, Kraven ends up fighting him.
Later in the film Dr. Connors can find Man-Spider fighting Kraven in yet another battle, and cure him permanatly of his desiese. Kraven is angered, pushes Dr. Connors down on the ground. Spidey starts fighting with Kraven, and then Connors turns into Lizard, and the battle will be very brief for Kraven (because he'll be knocked out). The battle will continue with Spidey and Lizard, and somewhere it would be cool to see Lizard knock Spidey off a building and they fight in mid-air, and then fall face-down on the pavement, break thru the pavement and go right into the sewers where Lizard has his last battle. It ends that Lizard somehow is knocked upconcious, and as he changes back to Connors debris falls on him, killing him.
Later in the movie Kraven plots to kill Spidey once for all (this time with guns). The battle leads to graveyard where Kraven drugs Spidey and buries him alive (coincidentally beside Uncle Ben's grave). Then Kraven goes back to the police officials and kills himself in front of them. (This being "Kraven's Last Hunt")
Finally Spidey wakes up and digs his way out of the coffin, and the grave.
The doctor tells Peter that Aunt May is dying, and shows him the medicine that will cure her. Suddenly the 2nd Goblin bursts in and makes Peter pay by taking the medicine and leaving. Peter goes after him. He finds him in his mansion where they have a final battle. And this time it leads Peter to doing an unthinkable thing: actually hurting him VERY badly without the symbiote's influence. Peter could possibly slam him into walls, punch him without holding back, and finally kill him because he doesn't give the medicine back.
Then they could show Aunt May dying because the medicine wasn't received by her earlier.
At the end of the movie they could show Brock and Kasady in prison, when the symbiote finds them and they become Venom and Carnage and break out of prison.