Back in the days when Bill G was the chief software architect, he was known for brutal meetings where he castigated engineers who weren't able to adequately defend their work. He had an overall vision for the PC-equipped universe through the 1990s, and that was informed by, and guided through, the software technology he understood best. So the key question one must ask in assessing whether he should come back focuses on his vision for the *next* ten years, and how that is informed by the technology he understands. He's not done a lot of work on mobile OSes and apps; by focusing on his foundation, he may not (yet) truly appreciate the challenges and forces that shape the mobile world that will be the major growth area in the next several years.
Will Larry and Sergey bring a renewed vision to Google, in contrast to what Eric Schmidt was following? Is Google succeeding because it does many things well, or is it doing one thing *really* well (search) which allows them to expand into other areas (cloud apps, mobile OS)? Alan Mulally succeeded at Ford by simplification -- selling off ancillary businesses, and focusing the efforts and vision on specific, achievable goals. Steve Jobs is succeeding at Apple by relentless focus on his vision -- a walled garden for mobile devices, a premium user experience with premium prices and margins. Perhaps Bill G would take MS back to a simpler, focused vision; but is that what is needed? IBM reinvented itself to have a large services arm, as well as its HW and SW divisions -- a manageable level of complexity.