I don't know... I think that if Henry was less ill and more inclined to marry someone else, he would have been more inclined to execute her to make way for a new wife... Don't forget, there were some strong Catholic political powers working against Katherine at the time, trying to get rid of this very protestant queen and set up a new catholic one. They would have arranged her execution if they could, be sure of it. She came very very close, IMO, and if Henry didn't die when he did, they would have succeeded eventually. In fact, if Katherine didn't find out about the signed order in advance and devised a plan, I have a feeling she would have been executed that time....