Doesn't make much sense to go into production with a new camera when the 5D2 is still awesome and the factories are geared to producing it.
#1 Possibly except they are spending money on R&D (supposedly) and we can assume that the 5d2 with the already stripped specs is not that expensive to make––surely less so than a new camera with newer technology. Save the money on R&D and lower the price.
The economics of running a high tech production line are not very intuitive. Manufacturing costs are relatively fixed no matter what level of technology is actually being assembled.
This is similar to the manufacture of hard drives. For example about 5 years ago you could buy a 100 gigabyte hard drive for $100 dollars. If hard drives were like other goods, where the price of manufacturing them comes down as time goes by you would expect that you could now buy a 100 gigabyte hard drive for say $50.
This is not the case. Instead you can buy a 2 terabyte hard drive for $100 - i.e. the unit cost has really not come down at all, as cost for each part of the hard drive has remained the same, but because of the R+D done you get much more space for your $100 of hard drive.
Similarly - continuing the production of the 5d mkII may not be cheaper for Canon than producing a new cut down version of the 5d mkIII. In fact if they stopped manufacturing mkIIs and released another camera that used the same sensor as the mkIII but with other features removed - they would probably see large savings compared to having to continue to have two separate production lines for sensors. (Production lines for producing sensors has to be more expensive than production lines for assembling bodies which is relatively low tech.)
btw Yes, I'm implying that Canon are making a huge profit per mkIII sold, but they have spent a lot on R+D, and people are prepared to pay that price, so fair play to them. As the price comes down over the next year or so, it won't be due to improvements in manufacturing process resulting in cheaper unit costs - it will just be slimmer profit margins for Canon.
Also I'm not sure how they could remove enough stuff from a 5d MKIII to produce a cut down version that is so significantly cheaper that it would get reasonable sales though. Pulling numbers from my posterior:
Remove SD card - $50
Change 61 AF points to 31 or fewer - $200
Frame rate from 6fps to 3fps - $200
Direct print button - $1
Even in a couple of years time when the mkIII is selling for $2500, there's not many people who would go for a cutdown camera for $2000 when the full 5d mkIII is only a little more. About the only thing I can think of is if they removed video then they could justify a much lower price (even if the manufacturing costs would actually be the same) and be able to capture more of the market.