Or will it just be added for free?
On XB1, multiplayer will be free and campaign/firefight will be paid DLC. On PC, it's all a separate piece you need to buy.
Bingo! Thanks for jumping in and helping share info! Reach campaign/firefight for MCC on Xbox will be a $9.99 premium add-on. For PC, it's just $9.99 for the whole game.