I'm going to say both Ness and Lucas return.
Now, Lucas is a character I COULD see cut, and it wouldn't surprise me if he was, but he has a few things going for him. He is BARELY a clone, the only moves he shares with Ness are his specials (which all have different effects) and his forward Smash. All his other moves are unique.
He is was also planned for Melee, and finally made it for Brawl. It would seems strange to remove him after he finally made it. He is also one of only 2 protagonists for the Mother series, and I don't think they would go back to having Ness as the only Earthbound/Mother rep.
I honestly think we will see less cuts then people think. Lucario and Toon Link are a testament to this. I also think that Star Fox and Fire Emblem are far more likely to get cuts then Earthbound.
By the way, I can find the article if you want. but Sakurai didn't say there wouldn't be any DLC, just that he wasn't planning on having any. He said he wants to focus on putting as much into the game as possible for launch, and in a later interveiw even said he is a fan of DLC done right. He brings up Fall Out 3 as an example of "good DLC." So DLC isn't completly ruled out yet.
