The Xbox One SDK is a tool released by Microsoft and sent to game developers, not released to the public.
If someone with knowledge of game development works with the HALT gang, they could release a version of the SDK that is open for anyone to use. That's a nightmare for Microsoft, as then anybody could create games for the Xbox One console and release them online for free, creating a "homebrew" industry.
This is one of the screenshots provided by the group which appears to show that they have access to the SDK software:
Anyone with the SDK still needs Microsoft's approval to release games. But if a hacker finds a way around that then the Xbox One could turn into a haven for upcoming developers looking to experiment with video games.
Once the SDK is out, people who have knowledge or has in the past reversed files related to the Windows (8) operating system should definitely have a go at reversing some files in there. Why? Well, the Xbox One is practically a stripped Windows 8 device and has introduced a new package format that hasn't had much attention. This format is responsible for updating the console and storing applications (Games are under the category of 'Applications' on the Xbox One) and is a modification of Virtual Hard Disks. There is no definite 'exploit' but from what we have studied and tested, this simple Packaging format could possibly lead us to creating Homebrew applications for the Xbox One.
The PlayStation Portable console was beloved by amateur developers because exploits in its software meant that anyone could design and release games for the console over the internet. PSP homebrew software remains popular today, despite Sony's continued efforts to crack down on the practice.