From my experience I'd say Canon could sell the 5D3 for $1500 and still would make profit. But as many are willing to pay more Canon takes more... It is that easy...
There's pent up demand in the market for an "affordable" (ahem) Canon FF camera with an advanced AF system.
The 5DIII delivers just that and many will pay the initial high price.
But the 5DIII is also meant to be a high volume product (relatively speaking), so the price will inevitably drop.
This is called "price skimming" and seems to have become Canon's standard pricing strategy for all of their photo products.