Not entirely sure what you're asking. At the time, what George made was episode I. There was no other story. It was just... the story.

But if you're asking if he had happened to have come up with the plot for The Phantom Menace first instead of the plot for the original Star Wars, I really don't know. It obviously would have been quite a bit different, as there simply would have been no way to accomplish a lot of the ideas. Who knows what the Jar-Jar equivalent would have been. Hell, it might have been better. We might not have had to sit through that boring-ass pod race sequence.

I don't know. It's an almost impossible question to answer. I mean, like it or hate it, The Phantom Menace exists as it does because the original trilogy existed. I mean, The Phantom Menace as it stands serves no other purpose than to tie back in to is predecessors. Without that as a precedent, I don't see how he could have possibly come up with a story at all like it.

But for simplicity's sake, I'll just go ahead and extrapolate and say that, word for word, it ended up on the screen. I honestly feel it wouldn't have been the huge hit the original Star Wars did, but, assuming the ILM breakthrough happened, I think it still would have been something of a phenomenon, and considered a groundbreaking pioneer in special effects at the very least.