Bungie + Activision appears to be the same as iD + Activision in terms of the contract they signed (at least according to Bungie's press release) with the exception of exclusive distribution rights for 10 years (where iD did it game-by-game). IW was more of a 2nd-party developer to Activision.

All that said I expect -- if Bungie's smart -- they'd have more than a few escape clauses in the contract.