To indulge the fantasy a little further (assuming the outer storyline stayed the same),TPM would have been much more of a political allegory if made in 77, which would have made it more "timely," and probably not quite as successful. Oh sure, if the ILM leap had occurred, and had TPM been crafted/scripted/edited with as much quality as the SW we know and love, it would have done smashingly, but in a more ordinary way. What really put SW over the top in popularity was that it was a movie completely out-of-time, something that had much more in common with ancient morality plays like Beowulf than any contemporary political/social/whatever concerns. This timelessness is such a big part of why people started showing up at screenings dressed like characters right away, and why it acquired such a reverential kind of following, way more than any other normal hit movie.