The 1960 version will be left alone. It will not be cut, taken out of circulation, or converted to 3D (at least I hope not). So there's nothing to worry about.
And it's quite possible that Spielberg and Kushner will make a very different and equally-good version. I doubt they'll do better than...
I don't understand why people get all hot and bothered about remakes. What's the worst thing that can happen? One more lousy movie that's forgotten in a few years, while the original remains loved for generations.
What's the best that can happen: Two great films that take different approaches...
I have no problem with remakes, as long as the originals are still available (which is usually the case). If a good director has an interesting take on a story that's already been filmed, it might be worth watching.
Also, I don't really consider the 1961 movie "close to perfect." It has a hell...