Microsoft currently offers OEMs a low-cost version of Windows 8.1 called Windows 8.1 with Bing. The OS is like the proper version of Windows 8.1 but the OEM cannot change the default search engine and it is less expensive to licenses as well; the OS is designed for entry level machines.
The reason Microsoft has this SKU is so that it can have products at the low end of the market with prices that are competitive to Google's Chromebooks. Because Windows licensing fees are overhead to the purchase price, they can be restrictive to the floor the price of Windows devices can reach when you factor in that the vendor needs to leave a bit of room for their margin as well.
So, to give OEMs a hand in pushing down the entry level price for Windows devices, Windows 8.1 with Bing was created and that SKU will be coming to Windows 10 according to Intel.
The company has released a roadmap of their upcoming processors for its Compute Stick and when 'Falls City 2' arrives, it will be designed for Windows 10 with Bing. For clarification, Windows 10 with Bing (much like Windows 8.1 with Bing) will be limited to OEMs only, so the only way you can get your hands on this version of the OS is to buy hardware that has it pre-installed.
Microsoft has been making a big deal that Windows 10 will be a free upgrade but if you don't have a PC running Windows 7 or 8, you will have to pay for the OS. So, even though it looks like Microsoft is undercutting its revenue with the upgrade offer, OEMs and the Enterprise will still have to pay for the OS and after one year, all consumers will have to pay too.