Peter Molyneux, President of Lionhead Studios, has always been known for having a sort of, well, let's say "optimistic" view toward his own games. It seems that he is yet again just as optimistic about his most recent upcoming work, Fable III.
Molyneux has told GamesIndustry.biz that he expects Fable III to sell over 5 million units in total and make over $150 million in profit. Molyneux may be a little idealistic here, considering both Fable I and II collectively sold about 6 million units.
Beyond the disc version of Fable III, Molyneux also announced he is going to release Fable III in an episodic format as well, in the same way that Fable II more recently saw a release. The episodic thing may work great in some cases, but for a game like Fable, a full download at once would probably be best. Best of luck to you, Peter.