This means many games with networking infrastructure to be played cross platform will be updated to work on Xbox One. The most recent title for now Rocket League. This means players on PC, and PS4 will be playing right along Xbox users.
The official statement from Microsoft below:
First, in addition to natively supporting cross-platform play between Xbox One and Windows 10 games that use Xbox Live, we’re enabling developers to support cross-network play as well. This means players on Xbox One and Windows 10 using Xbox Live will be able to play with players on different online multiplayer networks – including other console and PC networks.
Of course, it’s up to game developers to support this feature, and Xbox Live players will always have the option of choosing to play only with other Xbox Live players. We’re thrilled to confirm that Psyonix’s Rocket League will be one of the first games to take advantage of this new capability by enabling cross-network play between Xbox One and PC players, with an open invitation for other networks to participate as well.”
Who knows if Microsoft may now be able to get other titles previously unattainable due to networking restrictions. Final Fantasy XIV comes to mind first imwhen thinking of the implications of this announcement.