343 has said crossplay, input-based matchmaking and custom game browser will all release for Halo: The Master Chief Collection in 2020.
In a blog post on Halo Waypoint, the developer provided a snapshot of the features the development team is working on and committed to for 2020. Without providing specific dates, 343 confirmed a number of features players have been calling for.
Perhaps the highlight is crossplay between Xbox One and PC. 343 said crossplay, input-based matchmaking and server region selection will all release together.