Originally posted by SWFan4Life
As mentioned in the post above, it is only on video. But I will tell you exactly which scene. Go out and buy the Empire Strikes Back DVD and play it with audio commentary by George Lucas, Irvin Kushner, etc.In the duel between Vader and Luke on Cloud City, right after Vader directs Luke to fall into the carbon freeze chamber, the audio commentary has George Lucas saying,
"At this point, Vader's plan, now that he knows Luke is his son, is to convince him to come with him and join the dark side, and together they're going to overthrow the Emperor, which is the thematic device used through the whole movies, in terms of Sith, which is if you have Sith Lords, there's usually no more than two, because if there's three, then two of them will gang up on one of them, and try to become the dominant Sith. Anakin would have been able to do it, if he hadn't been debilitated, and now he's half-machine and half-man, so he's lost alot of the power of the Force, and lost a lot of visibility to be more powerful than the Emperor. But Luke has it, Luke is Vader's hope."
Notice how this quote talks about how "Luke has it" to become "more powerful than the Emperor" not that he has Anakin's potential.
Additionally, another quote from George Lucas:"Anakin wasn't what he was supposed to become. But the son could become that."
This is from the Rolling Stones magazine interview of GL, i believe.
That quote is taken out of context. You are right it is in the Rolloning Stones interview but when read what it clearly means when it says "the son could become that" is that Luke could become more powerful than the emperor.
"Which is what the Emperor was looking for in the first place: somebody who would be more powerful than he was and could help him rule the universe. But Obi-Wan screwed that up by cutting off his arms and legs and burning him up. From then on, he wasn't as strong as the Emperor -- he was like Darth Maul or Count Dooku. He wasn't what he was supposed to become, but the son could become that."