The special effects aren't what made the OT last, anyways. It's the story and character development that make the OT such a monumental sci fi epic. Yes the fx were excellent for their day, but even so they were used sparingly and usually moved the plot forward. As the PT shows, Lucas only used the fx sparingly because he had no other choice, give him a full buffet of fx with an OT remake and he'll load his plate up with everything on the freakin line.
My biggest problem with remaking ANH would be Solo and Obi-Wan; these two characters carried the film and Lucas could never replace them. Ever. In all three prequels, with a fine actor, Lucas has not been able to match the Obi Wan of the OT. Lucas has consistently throw away some of the best actors alive in the PT, for example, Liam Neeson never got a chance to shine even though he played one of the most influential Jedis in the entire series.
Lucas is done. I'm happy we got ANH and ESB, and although they reflect the time period in which they were made, that is part of their charm. The PT will one day show its age (in fact TPM already is showing its age with cartoonish CGI compared to ROTS). This is the nature of any art, and good art SHOULD reflect the cultural period from which it originated.
Ok, sorry for the rant, but in case it isn't apparent already, I have a low tolerance for flashy special effects. IMO effects should be seamless with the movie and the viewer shouldn't even realize their happening - full immersion. Like the first Matrix film. Effects should always move the story forward or add to character development. Lucas doesn't understand any of this.