Yeah see, I posted a thing about that before too, how the films seem to follow a method:
1. Villain
2. Mary Jane relationship
3. Question about powers
are the 3 primary parts of the stories
First one we have:
1. Green Goblin scenes
2. Everything about Mary Jane
3. Getting powers in the first place
Second one:
1. Doc Ock scenes
2. Everything about Mary Jane
3. Losing powers
But..see...I don't think there isn't that much about Mary Jane left. They've got a good relationship...and they spent an overwhelming amount of time on her in the first two, over half the films. So they shouldn't spend as much time on her.
1. Venom
2. Mary Jane relationship is replaced with Eddie Brock relationship
3. Symbiote and Sandman
See I think part of the side-effects of the symbiote would be Peter pissing off MJ, so that kills 2 birds with one stone. Plus, Brock would know everything about Peter, so he'd know about MJ, and there we have how he can abduct her for the end fight, cause he knows how they're together. I think they could pull it off, but, of course, only if Sandman has a small part. As for GG2...I still just don't see it happening.