Microsoft still had right of first refusal for their next project, which was Destiny. They didn't want it so they went with Activision and Sony got the marketing.They went to Activision but didn't Bungie want out of the contract and fulfilled it with ODST and Reach instead of Halo 4? Why would they want/accept an exclusivity deal if they wanted out? I don't understand who Microsoft could have passed on signing Destiny to be exclusive if Bungie wanted out? There's nothing there to pass on because Bungie would have been gone.
Think of it like Borderlands before 2K bought Gearbox. Gearbox couldn't go anywhere else even if they were owned by Embracer.
Here's an old article from 2007:
The source said that not only does Microsoft retain the “Halo” intellectual property, but they also get the right of first refusal of all new Bungie properties, adding that because Bungie is now based right next to Microsoft in Kirkland, Wash., there’s always going to be good communications between the two.
‘Halo’ creator Bungie splits from Microsoft
Just a week after the spectacular launch of "Halo 3," the developer of the game, Bungie Studios, announced it is splitting away from Microsoft and to once again become an independent company.
www.hollywoodreporter.com