After the surprising move of Don Mattrick leaving Microsoft to become the CEO of social games developer Zynga, there's a void that needs to be filled at Microsoft. According to Bloomberg, Steve Ballmer is poised to have Julie Larson-Green "oversee hardware engineering for all devices, including Xbox gamin consoles and Surface tablets."
Larson-Green is currently in charge of the Windows division at Microsoft and has been with Microsoft since 1993. The proposed move of putting Larson-Green in charge of hardware engineering for the whole company would make her the successor to Mattrick.
Ballmer is still restructuring roles and reorganizing the company's execs, so none of this is confirmed yet. However, one has to think that current key Xbox One executives Yusuf Mehdi, Phil Spencer, Phil Harrison and Marc Whitten are also being considered to take over.
I don't know enough about Julie Larson-Green to speculate whether she would be a good person to be in charge of the Xbox One, but my personal favorite would be to have Phil Spencer take over. Microsoft has a PR problem right now, and Spencer is a face and personality that comes off as likeable. He's also responsible for building gaming and entertainment on Microsoft's PC, mobile and Xbox platforms. With his most recent appearance on Jimmy Fallon, and him wearing a Crackdown shirt, he's a guy that knows games.
That's what Microsoft needs in charge of the Xbox One — someone that understands games.