He could play an active part in turning Microsoft's devices and services around as well as creating new products    



From DailyTech:

According to Bloomberg, Gates may take on a product development position that shapes Microsoft's future devices and services. This could be a great move, considering Gates was the one who originally threw around ideas for smartphones and tablet PCs at Microsoft before Apple launched its respective products -- meaning he could bring some great ideas to the table and try to push ahead of competitors.

Microsoft has been struggling in the smartphone and tablet space while competitors like Apple and Google/Samsung dominate mobile. According to TechCrunch, Android's global market share surpassed the 80 percent mark as of November 2013 while Apple's iOS was at 12.9 percent and Microsoft's Windows Phone had just 3.6 percent.

  Bill Gates Could Take Hands-On Role in Microsoft's Product Development