I disagree with most of the above.
First, one got to understand that movies are a business. The business of MGM, Fox etc is not to release once a movie and that's it. It's to re-release it over and over as long as it sells. Also one got to understand the market is made in such a way that an old barcode is considered obsolete and will not have the same sales attentions, from the shops and sellers, and distributors, as a new barcode. So films are refreshed over and over as long as they sell.
4K and HDR is a leap in color space, just like the leap between 256 and 4096 colors with monitors. Sure the added resolution is not as big as the one between DVD and Blu-ray (just twice), but the HDR makes a whole difference, meaning more accurate colors are now possible when it comes to old films.
I agree with mixes, however, often the remixes loose the dynamic range, and it's preferable for the original theatrical mix to be included, in lossless.
As for T2 3D I'm looking forward to it and the new scan. I don't get what this guy is on because the only thing in T2 Blu-ray not looking like the original prints is the color on the first scene with the bikers (it was bluer in cinemas, but was color timed clearer and orangey for the LD/VHS on, for clarity). I hope the new scan fixes this back to the original color. That's it.