I agree with the OP that no Clint movie should be remade. It would be sacrilegious to see anyone other than Clint.
Cool Hand Luke should never be remade. No one can replace Newman, Kennedy, and the warden (I forget the guy who played him) If they do, what they would have here is a failure to communicate the essence of the movie.
No Hitchcock movie should ever be remade and several have tried and failed. (except of course when Hitchcock remade his own 'the man who knew too much', that was good).
I heard Das Boot is being remade and that is a shame. I bet it will have more modern special effects and stuff, but I doubt they can ever capture the gritty, lonely, suspense the way Petersen did.