I think... the original ending was in the TGS 2010 trailer.
When he says, "My name is Dante," he smiles and jumps off a building and escapes. There's a blue blur right above him with a shiny sliver of metal... most likely Vergil diving after him with the Yamato.
When the trailer ends, that's probably when the original ending ended as well.
After the credits, you see Dante like about a year later, with his white hair and red coat. And on the run. Vergil is on a cathedral, looking down upon him. Then it zooms up to his hand, and he flicks open Yamato with his thumb. End scene.
You're probably asking, "What about the scene after that where Dante is laying down on top of a gargoyle and smoking? That's probably a flashback. It changes to present day white haired Dante (who no longer smokes, and is eating drinking tomato juice instead of smoking). And while Dante changes, the city changes with him, revealing the passage of time.
THEN you see Vergil on the cathedral, looking down upon him.
Look, I'm most likely 99.9% WRONG on this being the original ending, but that's just how I imagined it. It's just a really wild guess, nothing more.