Microsoft is running a very confusing strategy here. Google understood that with Motorola and it's why they sold it off. Microsoft hopes to keep its monopoly in the PC space with its multi-OEM operating system, yet still try to get every PC consumer to buy its own devices. Something's got to give.
I expect Microsoft's partners will increasingly continue to push other operating systems into the market on their devices, even if initially it's not exactly what the market wants. But they will do it anyway, because they will increasingly hate Microsoft.
And it will work, because the PC ecosystem is much bigger than Microsoft, and Microsoft won't succeed fighting against it. They will lose more money from lost licenses than they will be making (in profit, since so far Surfaces have continued to lose them money) than they will be making from these devices.