Okay so in The Amazing Spider-Man 2 it seems pretty clear now that the Goblin or a Goblin will be an important plot point, Due to the trailer we know there will be a fight sequence between Spidey and the Goblin at some point and due to what I've seen and read from other peoples comments most believe the Goblin in this movie will be Harry as played by Dane DeHaan.
At first I hated this idea but after thinking it over this could be a better route.
Now obviously I could be wrong as I haven't seen the movie or a script and so going on guesses and instinct I'm going to tell you my idea as to how the Goblin story should go in these movies.
Okay in the trailer we saw a what looked like a very ill Norman Osborn my idea would be that Norman will take a back seat in this movie and that would be if not the only then one of the only times we really see him in this movie, I think that the less we see of Norman in this movie the better as the scene's we do see him in will be even more important.
Harry becoming the Goblin could be one of two things if my guess is anywhere near to being right, Either Norman pressures Harry to under go a procedure turning him into the Goblin in order to hunt down Spider-Man believing his blood may hold a cure to whatever is killing Norman or Harry distraught as his father faces deaths door goes to Oscorp and turns himself into the Goblin only to try and take down Electro and Spider-Man due to his new Goblin nature.
The idea of the Goblin taking care of Electro came about my head due to after seeing the Goblin in the trailer I remembered a quote saying "Electric dosent die it simply goes away" or something similar when someone was referring to Electro, maybe the Goblin interrupts Spidey and Electros big fight and knocks Electro back only to come back to him later offering him something (I'll get back to that) this could lead to Spidey and the Goblin fighting (the scene we saw in the trailer).
Now I'd prefer this movie didn't kill him off but after this fight Harry could die due to the procedure making him the Goblin taking over his body and killing him or he gets hurt loosing his memory or sending him into a coma.
This would lead to Oscorp retrieving his body and later finding out Harry's blood now holds the cure for Norman, if this is not shown at the end of the movie it could be shown during the third or better the fourth I say better as it would leave the third to tell its own tale.
When Norman finds out there is a cure in his son's blood he takes the chance not thinking of Harry's well being and cure's himself killing the Oscorp staff that know about this, But the cure comes with some side affects and mixed with his illness this turns him into the Goblin and I'd like them to use the Ultimate version as this take for those that don't know is a big green beast with spikes and can form flames at will thus being a very deadly opponent for Spider-Man if not his most deadly.
After a small fight with Spider-Man (in the forth film as I said before) which leaves Peter scared at the brute force behind this new enemy he has just encountered not knowing it is in fact Norman Osborn, Norman leaves the scene not to be seen again unless..... The Sinister Six movie takes place before the forth movie which opens a new idea on its own.
The Sinister Six -
In the Sinister Six movie Norman would have been away after receiving his abilities from the cure he took from his sons blood, after hearing of the news of Spider-Man defeating Doc Ock and Vulture (who I'd like to think will be the focus of the third movie after their references in the trailer) comes back to New York and finds them in the unit they've been imprisoned (remember that picture of the unit saying Sinister Six released not long ago) breaking in he tell's them along with Rhino and Electro (unless as I said before he was offered a chance to leave the fight so that he could be put to more use later) that he has a plan to ruin Spider-Man once and for all.
Now this movie wouldn't Feature Spidey as hopefully it would be about the Sinister Six as characters and explore them more, So it would show how they work with Norman seeing himself as their leader making plans he keeps to himself and only seeing Otto as somebody on his level scientifically and in terms of IQ.
I haven't yet thought of a route to take this movie but I'd like to see them on the run and to come out alive and well in the end, You'd have to introduce a new character to make them six so why not throw in Kraven the Hunter as a man who hunts them down but then joins them.
The Amazing Spider-Man 4 -
In TAMS4 the Sinister Six would return as Norman's grand plan comes into action and again in an Ultimate route he'd have by now realized that Spidey got his powers due to Oscorp and see's Spidey as his property and so he uses Spidey blackmailing him into joining them but this would turn around and end with Spidey defeating them all and if you really like Kraven could do the whole 'Spider-Man 3 Sandman thing' and go "I've seen the error of my ways" due to never really having a cause to join the Six apart from his own reputation as well as as Spidey confront Norman, Norman beats Peter near to death when suddenly Harry now remembering all that he did as the Goblin decides he has to save his friend and kill his father ending Norman once and for all.
Now you could think this all sounds crap but would love to hear what you think and if you guys have any theories so thanks for reading.