^ Well, they have shown that right now they are only looking at the 4 movies. And we know that the Goblin will be highlighted in at least number 3, if not both 3 and 4. He will likely even get a quick scene where he drops something at the end of #2.
As I've said elsewhere, there are two ways they can go. One is with Green Goblin being taken down in #3 and then Doc Ock, a character introduced in #3 would bring together the Sinister Six in #4; or they could forgo Doc Ock and make the Goblin the leader of the Sinister Six. If you really look at the signs, this is what seems more likely, that Goblin will be the leader of the Six, which means possibly no Doc Ock, or he'll just me a member of the Six.
Also we know they are trying to go bigger and badder with this series, which again is 4 movies. So the final movie will likely be the biggest one. Which means a build up in number 2, to what quite possibly will be a part 1 (movie #3) and a part 2 (movie #4). The fact that they expanded to 4 films kind of shows this possibility, that they are putting into two movies what they were going to put in 1.
So, instead of giving you what I would like to see, I'll give you what we will likely be given:
ASM3 - Depends which way they go. One way is Goblin is defeated leading to a Doc Ock lead Sinister Six in #4. Likely is Sinister Six formed (with Goblin as the leader, Rhino = muscle, Vulture = flight, and 3 others, possibly Electro will be back, Lizard could be reused and Black Cat could be "somewhat on the baddie's side", Black Cat will be featured as both a "villain" and a "love interest" for Peter (kind of). So, which villain will be defeated (you always need at least one)? I'd say Rhino.
ASM4 - Sinister Six will be defeated. Spidey will need help from Black Cat (and possibly others). Symbiote suit could even be used (experiment in a lab as Oscorp, invented by some dude names Otto). One easier way to get through six is to spread it out over two movies (a Sinister Six part 1 and a Sinister Six part 2). But also they could use some characters in the Sinister Six that would "switch" sides and either leave or take out one of the other Six. For example, Black Cat could switch sides and take out one of the Six (which really takes care of 2) and/or the Lizard (Connors), who is being forced to work for Osborn, could either just slink away or take out one of the Six and then escape. Both of these results in a two for one, meaning there would only be 2 baddies left. Spidey takes out the 5th and then goes after the Goblin for revenge.
At this point they will likely need to recast the characters. The year would be 2017/2018 so maybe a new Peter and a new MJ. Maybe not, but at some point Gerfield is gonna be done with all of this and after movie #4 would be the best time to make the changes.
TASM5: Doc Ock (if he wasn't used as part of the S6) and the symbiote. Venom is created!
TASM6: Venom. He's in Ravencroft at the end. A post credit scene shows him locked up and a small piece of the symbiote splicing off of him and crawling it's way to the next cell, which houses the insane Cletus Cassidy, who is rambling about wanting the power and teaching the world a lesson, stuff like that. He sees the symbiote offspring, stops rambling and smiles. Fade to black...
TASM7: Maximum Carnage. Spidey will need to break Venom out of prison in order to take down Carnage. Could use Shriek here as the pycho girlfriend of Carnage.
At this point the year would be 2024, so who knows what will happen after.
So many places to go at that point. Agree that Kraven's last hunt would be a great story. I would tie in Chameleon since they are brothers.
Morbius would be another good one, but the whole vampire thing is a bit over the top.
Then there is Scorpion, Sandman, Tombstone, Silverman, Shocker, Mysterio (who really deserves a movie) and so many more. The material allows this universe to just keep going, and we're not even getting into possible crossovers with the F4.
Hopefully they won't screw up, but so far Sony has a better track record than Fox (in spite of Spider-Man 3), so fingers crossed!