The bridge scene was only conceived as a way to kill off Gwen. If they didn't decide to kill off Gwen then they wouldn't have told that story.
They only killed off Norman Osborn as poetic justice for having murdered Gwen. If they didn't kill off Gwen they wouldn't have had any reason to kill off Norman.
The idea of Jackal creating a clone of Gwen Stacy was a result of Stan Lee telling Gerry Conway to bring her back to life. If she was never killed off, then Jackal wouldn't be creating clones.
If Gwen was never killed off then JMS would never have come up with the long-lost-children idea.