While I'm sure the movie (if it happens) will draw at least somewhat on the events of the previous two Arnold films (hopefully more the first than the second), I do hope the writers look to the original REH materials for more inspiration.
One of the things that disappointed me about the Jason Momoa remake was that it was basically the 1982 film again, instead of a new plot, using Howard's stories as a basis. The Milius version drew heavily on Howard for themes and imagery, but the story was original. That's a good thing. But for the 2011 film to rehash a story that was only "inspired by" the classic tales is like a copy of a copy: It's just not as crisp.
Just of the top of my head, here are a few stories that -IMO- would make great fodder for the screen:
- Red Nails*
- The Jewels of Gwahlur
- Queen of the Black Coast*
- Hour of the Dragon
- The Scarlet Citadel
- The Devil in Iron
*Unfortunately, the 1982 film already used Valeria (Red Nails), and Belit's line about coming back from death to save Conan. They were awesome callbacks to the stories, but it makes it harder to use the rest of those tales.
Hollywood is going to do what they're going to do. And if the film is ever released, they have my money. But I can dream, can't I?