Good point about Sarah. It seems more like she was let go (with the option to resign), and you do that suddenly. Back to the chicken board with ye.
Phil seems a different case to me, though. Unless we assume he was lying, he had talked to Satya about retirement last year. And there have been rumors swirling about his retirement for years now. I think those rumors had some basis in reality. It also makes sense, if I put myself in Phil's head, that he would want to retire soon. I mean, consider how bad things have been for him the past two years. His grand vision for Xbox has failed spectacularly. The 80 billion in acquisitions he championed turned out to be a stressful and costly mistake. He had to close a lot of studios and fire thousands of people who worked under him. Despite his assurances, Xbox all its core exclusives to Sony and essentially waved the white flag in the console race. He got a ton of negative publicity.
If I were him, I would want to go, not hang around and try to smile through it all, keep up the PR show. I would know my time was over. So, I do think he was aiming to retire.
On the other hand, I don't think he was aiming to retire quite so soon, lol.