From everything I've read so far it seems my concept of the Sinister Six being next is correct. So unfortunately this poll doesn't work, since teams weren't included.
That being said I think it's safe to say we're going to get the following in TASM3:
The Gentleman working behind the scenes to help Harry bring together the Sinister Six with the following members:
Goblin (Harry)
Octopus (I, unfortunately, don't think it's going to be Otto)
Vulture
Rhino
The above are almost assured. The other two will likely, since I am now convinced that the Sinister Six will be told in just one movie, two villains that we've been introduced to (for one of them, kind of) and ones that will help speed up the story by not really being "bad" guys.
So the two I'm talking about are:
The Lizard (or Doc Connors for the most part), and
Black Cat
I guess Electro could take one of these two's place, but I need to see TASM2 to make a fair determination.
So, if the Six are the next villains for TASM3, and we know (at a minimum) there will be a TASM4, then who would be after?
My best estimate would be Venom.
This could be done pretty easy as it could be something being developed at Oscorp (by the Doc Octopus guy). Maybe he even needs to use the tentacles to work on the stuff since if it touches skin it absorbs in. Something like that...
The real question is whether it will be Brock, or not?
One of my worries though is that once they give us Venom and have him defeated by Spidey, they will go to Carnage, but make it a Venom movie and not an Amazing Spiderman movie. I believe that would be a huge mistake!
I want to see Carnage done in a way where Spidey needs help and is forced to break Venom out of prison in order to take on Carnage and his entourage!!!!!