Well, actually, I think they didn't do their math very well.
If you read in here -
http://www.anandtech.com/show/4143/the-source-of-intels-cougar-point-sata-bug on Anand's analysis (The "It’s Notta Recall" paragraph), you'll see that the cost Intel estimates comes down to more or less full motherboards - $87.50 per chipset, which kind of makes sense, even if they don't have to make a whole new motherboard, it still costs to desolder the old chipset, labour, and testing, packaging, etc.
The thing is, all the stores and the distributors also have a stock of Core i5's an i7's they can't sell. Well, they can, but nobody will buy a CPU without being able to buy a Motherboard until March or April.
So, the stores will want to receive Nehalem based CPU's for free and only pay for them once they can restart selling SB CPU's. Or they will want to return the SB CPU's and get Nehalems in exchange. Either way, Intel must account for the CPU cost part of the equation, which I think they haven't (at least publicly).
It's unclear how they are going to handle the situation, but this is not going to be easy for them in the next two months.
And even consumers are left in an awkward situation. They can't return the motherboard now, because there is no fixed motherboard available to exchange with, unless they can also return the CPU (but what if they bought it from a different store ? - how is Intel going to handle this ?), and chose to get the money back or exchange with a Nehalem based system instead.
And what about consumers that use more than 2 Sata ports ? It's actually quite easy to happen: 1 main HDD + 1 DVD RW/Blu-Ray already fill both Sata 3 ports. With more and more people buying a second HDD to store videos and photos (or a low capacity SSD to boot from, putting the HDD as the "documents disk"), you're walking into trouble already.
How does the store solve this problem, especially if you bought the CPU and motherboard from different shops ? Does the motherboard seller give you a PCIe sata add-on card for free so you can solve the problem ?
This is a PR nightmare.