I think it might be tough to produce a pro-grade FF camera, even if its bottom-rung pro-grade (i.e. xD), for under $2000. Part of the reason FF sensors cost so much, (and part of the reason MF digital sensors are only found in $10k-$60k cameras) is that they consume a LOT more silicon wafer space than smaller sensors. You can make about four APS-C sensors for a single FF sensor, not to mention the fact that defects in the wafer itself can cost a lot more as well, as a single tiny defect effectively ruins a whole sensor. With APS-C, you might lose one or two sensors to a defect, but thats still HALF of a single FF sensor.
The materials used to manufacture wafers and the systems that etch them are becoming much more valuable in this day and age as well, where electronics are orders of magnitude more important on a global scale than they were a decade ago. Many of the materials used in electronics are very rare (rare earth metals and the like), and there are few providers for such materials. China was a huge exporter of rare earths and other commodities used in electronics, however they have been holding onto supply for their own internal uses and rumoring they will cut it off completely, which has been driving prices through the roof (which is actually good news for some upstart American rare earth miners!) I think it would be surprising to see the 5D III remain at $2500 if this trend continues, and I wouldn't expect a cheaper sibling to break out below $2000, if it happened at all.
Maintaining profit margins is extremely important for an innovative company like Canon that has a large R&D sector...those profits are banked towards future innovation and investment in continued R&D, which just means more competition and better tech in the future for us consumers.