Halo: The Master Chief Collection will get Xbox-PC cross-play in 2020 - Polygon

In particular, the developer said in an update on the Halo website that it’s looking to bringing cross-play, keyboard and mouse support on Xbox, and input-based matchmaking to The Master Chief Collection by the end of 2020.

Cross-play, input-based matchmaking, and server region selection are expected to launch together, with a custom game browser and mouse and keyboard support for Xbox launching as a package.

Cross-play means that players across Xbox consoles and Windows PC will be able to play together.