Way I see it, Norman's return from the dead was inevitable.
The Green Goblin is always going to be around in some capacity because he's too significant to Spider-Man's world and let's face it, that's mainly due to Norman. Truth is, no one else was ever going to be able to fill Norman's shoes as the Green Goblin. Despite his best efforts, Harry was still in Norman's shadow and he came across more like Spider-Man's Two-Face than his Joker. Bob Harris made the right call in having Norman be the mastermind behind the Clone Saga because of how personal the feud between Norman and Peter was and still is, IMO no other Spider-Man villain would've had the same level of effect.