Question for all the OEM mobile phone companies (except Nokia)

After taking a peek at both Nokia's and HTC's spec sheets on their offerings for Win8 phones, I have an interesting question:

Why doesn't each of the other manufactures just flash the new Win8 OS on their current flagship devices and just sell them?

Each of them has already put the time in on design and component selection, all they need is the "drivers", I use that loosely, for the radios (Cell, Wifi, Bluetooth, etc) and Cameras

bang, Galaxy S3 Windows edition

bang, Galaxy Note 2 - windows edition (how much effort for the stylus?)

Bang HTC One X + windows edition (hell, I am betting that the internals in their Windows8x are damn near identical anyways)

LG, Motorola, etc....

I need to point out that the other componets are all basically from the same vendors, Cell radios, WiFi, etc (check iSupply breakdowns)