sony are mapping out this big spider-man universe because they want to keep the franchise. they aren't doing it to help out disney.
this recent reboot was their last shot. think how cynical the public would be if another spider-man continuity from sony came out in 5 to 10 years. people thought the amazing spider-man was too soon, and i guess in a way it was.. but that is forgivable seeing as sony would have lost the right if they had held off any longer.
so, sony knows this is their last shot. tasm made less than the raimi films, they know this, yet it turned a decent profit. another reboot in 5-10 years would likely make a few hundred million less than tasm1 did, and it wouldn't be worth it for them. so sony have no choice but to try and sustain this current continuity for as long as possible. how better to do this than to map out a universe and sequels and spin offs well in advance? not saying it will pay off, but they have nothing to lose at this point.
sony have looked to the success of the marvel universe, just like fox and wb have, and are universe building as a result.
the only problem is whereas fox and wb have the rights to a vast variety of characters that can have standalone films and team up films (fantastic four, x-men, batman, superman, justice league) sony has spider-man. that's. about. it. so they are left with having to expand spider-man's world.
how is this going to look? i'm not sure. but i could see an inverse avengers type movie via the sinister 6, and the venom spin off continues to be talked about. besides that, i think sony will just try and make spider-man's movies tie into the next much more than raimi's did. that way, it doesnt feel like just another spider-man movie, but a continuation of a certain story. this prevents people from getting as fatigued by the notion of an amazing spider-man 4,5,6.
what's interesting is, if the rights go back to marvel, how will they get around this public fatigue? well, unlike sony, they could wait as long as they need to reintroduce him to the silver screen. by then, enough time will have passed for people to not be cynical, and personally i am pretty excited to see marvel's take on spidey.