Microsoft is on the verge of massive change. CEO Steve Ballmer has announced his retirement, and the software giant doesn’t have an immediate replacement waiting in the wings. After 38 years with just two CEOs, the company is searching for its perfect match — someone to move software out of traditional boxes and into service efforts, an individual who can steer towards new a hardware push.

That’s a tall order. After months of searching, the company revealed last week that it’s not planning to name Steve Ballmer’s successor until 2014. While many had expected a new CEO by now, the search will continue over the holiday period and into the new year. Microsoft identified over 100 candidates and spoke with several dozen before focusing in on a group of 20 individuals. This group has now narrowed, and the current speculation is now centered on four key names: Ford CEO Alan Mulally, former Nokia CEO Stephen Elop, Microsoft cloud and enterprise boss Satya Nadella, and former Skype president Tony Bates.

Bill Gates says the Microsoft CEO role is a “complex role to fill,” and it’s clear there’s no immediate or obvious answer. While Microsoft’s board is assessing internal candidates, it’s a big decision to name a leader who will need to tackle a Nokia devices acquisition and a huge reorganization in the coming months. As the challenge of replacing Steve Ballmer continues into 2014, Microsoft employees, investors, and customers are left wondering who will lead the company into the next big trends in technology.