Windows 8: The end of the full retail version?

The Windows 8 start screen.

(Credit: Screenshot by Lance Whitney/CNET)

There's a rumor going around that, with Windows 8, Microsoft is doing away with the full version of Windows sold at retail.
If this pans out -- and so far, I have heard it from only one source (as I noted on the Windows Weekly podcast with my co-host Paul Thurrot this week) -- I doubt there will be anyone lining up in protest.
In Microsoft parlance, a full product typically means a non-upgrade, fully licensed version of Windows sold in a box via brick-and-mortar and/or online retailers. With Windows, full product tends to be quite expensive -- and not very popular, as most users get their Windows either preloaded on new PCs, via volume-licensing deals, or as an upgrade to an existing version of Windows. Very few users want or need a complete, new copy of Windows for a machine on which Windows has not been previously installed.
With Windows 8, Microsoft is being aggressive with upgrade pricing. Anyone with a copy of Windows XP, Windows Vista, Windows 7 or the Windows 8 Release Preview (with some caveats for Windows 8) will be able to buy up to five copies of Windows 8 Professional for $39.99 apiece through January 31, 2013. (And maybe longer, if Microsoft extends this promotional price.)

Those who typically have wanted and needed full Windows product -- among them, do-it-yourself PC assemblers -- will now be able to buy a system builder license for Windows 8. Microsoft officials have said the DIY crowd and those installing Windows 8 in a virtual machine or separate partition will be able to purchase a Windows 8 Pro System Builder version. There's no official word so far on the price of that SKU.
There's a bit of confusion among some system builders because hints regarding the new do-it-yourself (DIY) system builder license for Windows 8 seem to imply that those purchasing Windows 8 this way will only be able to obtain five copies per system builder for commercial use. For smaller PC makers, sometimes called white-box vendors, this limit is impractical. This limit also could hit companies whose IT departments may want to build their own custom PC systems.
Microsoft representatives are not commenting on anything to do with Windows 8 packaging, pricing, licensing, and distribution plans beyond what they have disclosed publicly already.
The company did say this week that Windows 8 is on track to be released to manufacturing (RTM) by the first week of August. It will be generally available by late October 2012, officials added.
Update: It looks like this rumor is likely true. One of my contacts forwarded me a system builder licensing document that includes this clause:
"The majority of consumers buying the retail license are looking to upgrade. For Windows 8, Microsoft will therefore only offer an upgrade version of Windows 8 through the retail channel. This is the license an end user would purchase who wants to upgrade their current PC from a prior version of Windows to Windows 8."