I don't think it's unreasonable. W10 support should be pretty damn good.I'd just like to remind that it's not DICE's stand, but one of their tech leads. He's also the guy who has worked on Mantle and Vulkan so it's no surprise that he's the first line supporting new APIs. As he admits, it's quite aggressive even with W10 being free to upgrade so I personally don't see them going for the DX12 minimum requirement next year.
And I see no reason to doubt the hype over DX12, either. Games built for it will open up a new level of possibilities.