Both the original Star Wars and Empire Strikes Back were officially added to the National Film Registry when it was created in the late 1980s. However, Lucasfilm never delivered an original, unmodified copy of either movie. George Lucas tried to give the NFR a copy of the "improved" edition, but they refused it; their mandate is to preserve original versions of historic movies.
The article notes that ironically enough, George Lucas argued against colorizing old black-and-white movies, yet he has refused to follow his own arguments with respect to his own movies.
I hope that Disney will deliver a suitable cleaned-up archival copy of the original, completely unmodified movie to the NFR.
P.S. I personally would be happy to have a version that has some hidden wire removal and other very minor cleanups. Probably the perfect way to do it is to release a new slightly-polished cleaned-up original, with bonus disc content of the original, cleaned up but utterly unchanged. Watching the movie over and over on a 4K screen, you will spot wires and other glitches to some extent... but there should be a version where they are perfectly preserved. It's a movie that was made in the 1970's. It was an advance in the state of the art of special effects, but it wasn't perfect and couldn't have been perfect. Sometimes it's instructive or fun to watch things and study how they were made.