Kubrick was no doubt a genius and mystery is a part of storytelling, the entirety of Eyes Wide Shut leaves so much room for mystique and interpretation that we can debate and discuss it forever but I did not find similar in the ending of 2001, it seemed like confusion for confusions sake with little deeper meaning.
This was all explained in very plain English in the book.
"Without consulting or confronting his co-creator, Kubrick cut a huge amount of Arthur’s voice-over explanation during the final edit... As it turned out, Arthur did not get to see the completed film until the US private premiere. He was shocked by the transformation. Almost every element of explanation had been removed. Reams of voice-over narration had been cut. Far from being a pseudo-documentary, the film was now elusive, ambiguous and thoroughly unclear. Close to tears, he left at the intermission..."
(full article: https://www.newstatesman.com/culture/2017/01/close-tears-he-...)
I think Kubrick and Clarke could have perhaps found a compromise. For example, I remember liking the ending part of the movie "A.I. Artificial Intelligence" by Spielberg which had a similar situation to the last sequence in 2001. I don't recall if that movie had any explicit explanation of what the beings at the end were but it was pretty clear who they were and what they were doing from the way the movie handled things.
I thought Spielberg ruined AI btw. But that's a different topic. I thought the final scene was the only good one in the movie. The imagery and implications stuck with me for decades.
If you make the connection that "monolith = jump in tech" then the ending, for all it's surreal imagery, follows as a jump so massive that of course a normal person couldn't understand, and it's all visualized in a super creative manner.
I wouldn't have guessed it was literally the aliens downloading his brain or whatever and that he'd chosen to go back and help earth, but the general gist is more than there. And i love the idea that it basically conveys what you need to understand, while also conveying what it would be like for a human to crash into something so phenomenally beyond what we've ever understood or experienced.
The books are actually quite easy to read and as much as I adore the movie of 2001, I think the book's ending is even more visually spectacular. Highly highly recommended.
I'm really glad to read this. Kubrick really lost me at the end. I thought I was just not getting it. The first 2/3s though are as good as any film I've ever seen.