At today's Windows 10 event, Microsoft and Lionhead Studios showed off the ability for Xbox One and PC users to play with (or against) one another across platforms in Fable Legends. The company didn't mention whether this feature would be coming for any other games.
It seems likely, though. As part of a news release, Microsoft mentioned a new Xbox Live API:
"Xbox Live is social, interactive, and seamlessly integrated directly into Windows 10, bringing gamers the experiences they love across devices, like multiplayer gaming on Windows 10 against players on an Xbox One, and messaging and chat with friends. And developers will get full access to the Xbox Live API, making it easier to create more powerful gaming scenarios across devices."
If developers want to implement cross-platform play, the feature should be available to them.