http://news.xbox.com/2016/03/14/letter-chris-charla-idxbox-updates-gdc/
Cross-Network Play
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.
Personally I don't see the big deal, but this is something a lot of people have been asking for. Lock if old.
This begins with Rocket League playable between Xbone and PC users, but theoretically not only could PSN join the fray (if Sony allows it) but this could mean for instance.. Titanfall 2 on all platforms sharing one unified community. Calls of Doody playable on all 3 (4 maybe.. NX?) platforms sharing one community. Exciting possibilities if these ever come to fruition.
Essay Pro