What should happen in my opionion...
Ned gets all his memories back EXCEPT for the person under the spiderman mask (cuz peter doesnt exist) so he remebers going to school with spiderman, but all of his class mates say that never happened, and his 1st friend was MJ... but ned remembers it, finds spiderman on a rooftop, and spiderman denies everything BUT spiderman says goodbye ned without ned ever saying his name to spiderman... this is ned's villain arc...
Obviously in SP4 he shoudlnt be the main villain, but a supporintg villian similar to harry osborn in TASM2... figures it our halfway into the movie... and he finds out a prototype suit green goblin made while he was still on this universe. and bom hobgiblin story.
I think spiderman 4 shoudl focus on Scorpion and venom.
Have symbiote spiderman injure scorpion to the point where he begs for mercy... and then peter realizes what teh symbiote is... (IDK how to write a symbiotes story...)