According to a report on ZDNet, "Threshold" will include updates to all three platforms that will "advance them in a way to share even more common elements," with the goal being for all platforms to ultimately share one storefront. Microsoft is also working to bring parity to developer tools across all three platforms, in the hopes of attracting more multi-platform applications.
The codename "Threshold," while likely chosen due to the initiative's goal of removing the boundaries between Microsoft platforms, also has a coincidental link to the Halo universe. It's the name of the planet you'll see in the distance beyond the original ring-world in Halo: Combat Evolved.
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