I enjoy the novel, but I feel a film adaptation should have the character of Rebecca played by an actress. The novel is so much in the head of the narrator and seen through her gauche, charming attempts to live up to her predecessor, that I don't think you can make a film without bringing Rebecca to be flesh and blood because you can't have a film that it is all internal monologue. We need to see Rebecca's glamour and confidence.
You can make a bold film about Mrs Danvers' menace, and creating the atmosphere of the house and the boathouse, but just the acting of the other characters won't bring Rebecca to life.
I read the cast list and couldn't see an actress playing Rebecca, so assumed she isn't figured in flesh and blood.
I also think that Mrs Dr Winter's character is brought out by the contrast to Rebecca ( who would be better played by Lily James, in my view). The contrast is like crimson velvet and beige lambswool. With Lily James playing the second wife of Maxim, with a romantic feel throughout- no doubt, it will be like crimson velvet tamed by the producers down to pink nylon.
But, the novel and film will give us an excellent boy's name to choose. No more procrastinating over Felix or Kaspar to be original, go for Maxim.