They will be redesigning the 360 later this year to use a new 65nm CPU (vs 90nm) and if it's ready a new 65nm GPU too.
Both will be cheaper to produce, but also run cooler and draw less power. There is a very good chance that it will be cheaper and more reliable.
No ETA yet, probably not until close to the holidays. They might drop the price on the old one just before then to dump stock though.