From Game Spot:
A number of exciting new features and pieces of content are coming to Halo: The Master Chief Collection–like a brand-new map and mouse and keyboard support on console–but fans will have to wait a little while longer to try them out.
343 Industries’ Tyler Davis said on Twitter that the planned beta test–or “flight”–has been delayed. It was previously scheduled to potentially begin on February 18, but the studio has encountered some “blocker” issues, and as such, the team is taking extra time to make sure the beta is smooth when it releases to the public. The new target date for the beta test will be sometime next week. The studio will share more details today, February 19.