This is a terrible idea. Microsoft going into the hardware business will drive out all the OEMs. And soon, the only one making Microsoft hardware will be Microsoft.
I hope MS learns from Apple. If you want an iOS device, you have to buy it from Apple. A monopoly can only drive up the price. Consumers lose.
Microsoft designs it and farms out the manufacture. It is almost the same analogy as running a fabless circuit design house. I dont know for sure if the OEM's will care that much if they can be one of the sources. I think where Apple won this battle was that when you bought the hardware, everything worked and was qualified. Grandma does not call tech support as often. Its easier to do this with tablets and phones. PC's still enjoy a build your own environment and this will NOT change. Too many varieties of a PC in all kinds of weird places where they run strange hardware for specific purposes. Ships, Factories, Sewage pumping etc. (there is more than just the web for computers to be useful)
So in the long run Microsoft has got it right as far as where to do the new stuff. The PC is more mature and needs less investment. It will be nice to have a Microsoft store right next to an Apple store and see them duke it out.