Halo MCC: 343 Industries is working on cross-play and mouse and keyboard support
And for those who worry that these novelties will introduce an unwelcome disparity in online arenas between controllers and keyboard and mouse users, 343 has made it clear that along with these features will also come matchmaking based onthe control system, so players will only be put together in the game if they are using the same input system.
The developers also explain that there are other innovations in development, such as choosing the region of servers to play on, to avoid being hosted on servers that are too far apart, and individual graphics and audio settings for each game in the collection, rather than global.
If these features are in development for the MCC, they are likely to also arrive in Halo Infinite. If that's the case, we'll find out in the next few months.