Now follow me here... Nobody wants a full ORIGINS movie right?
Well on SMALLVILLE they have shown how he lands, and is found on earth! But his departure from Krypton is not shown... EVER!
In a new Superman movie they can show all the Krypton scenes, and have the ship leave for earth, and after it crashes they could put a caption on the screne "25 years later" or something which helps us catch up to modern day, and the next scene picks up with Clark getting to the front doors of the Daily Planet. Maybe have the scene follow Clark walking in traffic a bit before he gets there as part of the scene build up... As Clark walks into the planet he sees old friends "Lois, Jimmy, and Chloe" (hope shes alive by then still) standing around talking, he walks up to them, and they don't seem to have any memory of who he is... I would make that part of my plot twist!
heh why did they forget him? Also this makes it easier for it to be believed that they don't notice that Clark Kent is also SUPERMAN!
Now this way you can skip the ENTIRE Smallville origin, and show something that shows us a part of these characters past we haven't scene like WHY Krypton exploded! There is a lot that can be done with this idea, and then tie it in with a new villain showing up in Metropolis. And yes my main villains in this movie would be DOOMSDAY! & Lex Luthor.
That's how I would write my Superman movie using the cast from Smallville.