It doesn't matter that Dune was previously adapted and Foundation wasn't. Prior adaptations could have been terrible, and this iteration of Foundation will be seen in 2042 the way 70s Lord of the Rings animation, or 1984 Dune, is seen today. I reject the premise you put in another post that there is some "test of time", some arbitrary number of years, that a book passes that deems it unfit for adaptation.
It's one thing to acknowledge the flexibility required in converting a story from novel to film. It is another to change the entire message, character motives and morals while merely retaining the surface plotlines.
For what it's worth, having read ten chapters of Dune after watching the amazing 2021 film, I can say they did a fantastic job capturing the spirit and the core storyline of the book.
