I can't wait until they start introducing the start menu back in Windows 8.2.
Start Menu is overrated.
But with new Windows 8.1 and Windows 9 coming up, I don't see why they'd make DX12 Win7 compatible. Win8 already has a desktop mode. Win9 most likely will have the same. And seeing as MS wants people off of NT/2000 architecture and onto WinRT, it just makes more sense to have all the newest, shiny things for Win8 and above.
But I could be wrong and I'd be ok with that.