It wouldn't surprise me if in the near future comapnies start releasing games in segments. Imagine if Half-life 2 was broken up into 4 chapters and each chapter was released every 4-6 months (real-world not valve time).
If your game sells good you keep making it, if it tanks then you don't.
Then at the end you can still release your "Brand new super duper platinum game of the year award version" (uh..I mean game of the two year award)