The problem that could occur is: Right now Microsoft doesn’t care about Linux or competitors, every OEM has to buy a Windows key anyways regardless. If SteamOS actually becomes a shippable option, Microsoft’s cavalier attitude is going to change quickly, and a lot sooner than it will take them to get an Xbox Handheld out the door.
Embrace, extend, and extinguish Microsoft’s gonna do what it does.
Why would an OEM need to buy a Windows license if the customer has no interest in using Windows?
It’s in their licensing, and how MS-DOS became the de facto operating system of early PCs. If you want to license Windows, you have to pay for every unit you sell - not just units with Windows pre-installed, but every unit.