Aside from the Re-elect Osborn for Mayor signs, I think some things that they've been talking about also could point to the Green Goblin thematically. They said for Mr. Negative's inclusion it was very important that he was linked to Peter's life since he's Aunt May's boss, and the balancing identities idea, them spilling into each side of the life, that all are things that ring true for Norman Osborn as well.
Plus exploring a Norman Osborn who maybe has reformed and been mayor for a few years, and having him go through a relapse could be pretty exciting story material.
(I don't think I've posted my thoughts on the footage but I saw it live and was blown away. I think it looks beautiful, but the way Spider-Man actually moves is unreal. Like it's a masterful acrobatic ballet, fully realized Spidey movement like I don't think we've seen on screen/anywhere other than some stuff in the Raimi movies. That's really cool and I'm excited about all the things I've seen from Insomniac's take on Spidey's world, was worth the year wait for more footage)