Not really a change ?
Currently you get low end Netbooks which run Ubuntu and better speced ones which run Windows XP. Your always given options but the options normally are there to limit your choice rather than expand it. Its easier to support 4 types of system than 400.
I'd see it as being sold like it currently is :
1. Cheap as chips with Ubuntu.
2. Average with Ubuntu.
3. "Premium" with Windows 7.
4. Ultimate with Windows 7.
From your average un techy punter Ubuntu is seen as a cheap but worse option, which is why so many people punt up the extra cash $20 is not a lot in the grand scheme of things.
I would not be surpised if a few manufacturers upped the price a bit more in order to make more of a profit and blame it on Windows 7.