Is sounds as if they are finally catching on, if this report is to be believed. I've been suggesting for a long time that Microsoft need to get to the market and to look to the long term for Windows users.
This option might be just what's needed.
Microsoft is considering making Windows Phone and Windows RT available free of charge to device makers. Sources familiar with Microsoft’s plans have revealed to The Verge that free future versions are under serious consideration by OS chief Terry Myerson. We understand the plans aren’t fully set in stone, but they’re part of broader changes Myerson is planning for the future of Windows. Report: Microsoft Considers Free Windows Phone, And RT For Developers [theverge.com]
I don't know the actual fees Microsoft charges for their mobile OS, but is it really that much? As no other major mobile OS developers seem to be charging for their OS these days I guess this was inevitable.