I think it would have been so much cooler if Ganema was still around in book 4, not as a sandworm but the EXTREME end case of the bene gesserit ability to alter the metabolism to basically stop aging. Their dialogue with each other in dune 3 was awesome and is something lacking in 4, clear, distinct conversations not clouded by 106 layers of leto II fucking with whatever human gnat he was speaking to. I also think it would be a sick contrast, and allow exploration of another perspective of the bitterness of the passage of time, leto is bored and complains about a lot of stuff, but imagine ganema a withered skeletal wraith, like golum but way worse, her perspective would be so different, excited for death and freedom from the golden path probably, just like leto, but very different