I'm hoping for updates to stop uninstalling or trashing software so that it has to be reinstalled after the update. Stupid.
The Linux command line or bash coming to Windows 10 is awesome. I think Microsoft is doing the right thing for Windows users by making it the best OS ever!
There is a lot of cool stuff in the build sessions. They will probably have another not yet announced pre-release event where while they may properly show all of the cool features though we should see most if not all in preview builds, also seeing the current number for W10 installs makes me believe that Microsoft will do something soon as the number is big no question but it's currently underperforming internal expectations, there is no way to reach the 1B at current growth rate. Some people will probably get fired or lose their position, I wouldn't really be surprised if they extend the free upgrade after all or do something more drastic.
DX12 doesn't require a new GPU, only DX12 specific features require a DX12 card but you won't be finding a game using them for quite a while, there is no hardware really to use them anyway.