Ballmer's Legacy Still IncompleteBallmer's Legacy Still Incomplete

But unless Ballmer's recent bets pan out, it's unlikely Microsoft will adhere so closely to "one Microsoft" as it is currently defined. Julie Larson-Green's prospects, for instance, will surely be informed by how the Xbox One fares against the PlayStation 4 this fall, how well the next round of Surface devices sell, and whether Windows 8.1 gains traction.

Indeed, Microsoft's board appears to be apprehensive about the company's direction. All Things D, citing numerous insiders, reported over the weekend that Ballmer's exit might not be as amicable as the CEO has implied and that board members evidently felt Ballmer's exit should come sooner rather than later.

There's also buzz around hedge fund ValueAct's alleged interest in gaining a seat on Microsoft's board and asserting more control over strategies it disapproves of, including, reportedly, Microsoft's decision to make its own hardware. Ballmer has denied that his decision was informed by the rumor, which has been touted loudest by Nomua analyst Rick Sherlund but is nonetheless reinforced by several sources. But whether or not ValueAct moves, Microsoft's board is surely aware that investor discontent has risen. Even if the company wants to follow through on Ballmer's plan, influential shareholders might not have the patience or faith to allow it.

And if Windows 8.1 flops not only among consumers but also among enterprises migrating off of Windows XP? One option would be for Microsoft to double down on new enterprise businesses. Satya Nadella, who ran Microsoft's successful Servers and Tools business and now oversees its Cloud and Enterprise group, could be in the running in this sort of scenario.

But if Microsoft wants to become an innovative company that spans the consumer-enterprise spectrum, it might ultimately look outside. A cultural overhaul would likely bring an end to the "stack ranking" system, for example, wherein a certain percentage of employees within a division have to be rated as sub-standard, even if all of the employees are producing excellent work. The result has often been company-wide dysfunction, with silos acting more like warring tribes than complementary assets. Despite calling for more collaboration, Ballmer has indicated the system might stay. If the company continues to flounder under that system as his tenure winds down, a change in blood might be necessary.

According to a research note by Wells Fargo Securities analyst Jason Maynard, if Microsoft maintains its "devices and services" goals, Nokia CEO Stephen Elop, whose company makes almost all Windows Phone hardware, might be the most likely outside candidate. Maynard noted, however, that Wells Fargo believes Microsoft should abandon this plan. Commentators have also suggested outside candidates ranging from Yahoo CEO Marissa Mayer to Oracle President Mark Herd to Tesla Motors and SpaceX founder Elon Musk.

But it's all speculation for now. Ballmer will make his case on Sept. 19, when Microsoft hosts its annual meeting for financial analysts. He'll also oversee a number of important events before leaving: the launch of Windows 8.1; at least a few new Surface devices; new enterprise products, such as Windows Server 2012 R2; the debut of the Xbox One; to name a few. The company will also continue trying to sell Windows 8 to companies that need to upgrade before Windows XP loses service in April.

Ballmer's execution in these tasks will determine whether his fingerprints are on the company's future successes, or just the things that the next CEO has to fix. They'll also likely dictate what kind of CEO Microsoft decides to hire.