http://techreport.com/news/26210/directx-12-will-also-add-new-features-for-next-gen-gpus
I wonder if second generation Maxwell will support all these new DX12 hardware features or we have to wait for Volta.
DirectX 12 will indeed make lower-level abstraction available (but not mandatory—there will be backward-compatibility with DX11) on existing hardware. However, Tamasi explained that DirectX 12 will introduce a set of new features in addition to the lower-level abstraction, and those features will require new hardware. In his words, Microsoft "only teased" at some of those additions this week, and a "whole bunch more" are coming.
So far, Microsoft has mentioned only two DX12 features that will need new hardware: new blend modes and something called conservative rasterization, which can apparently help with object culling and hit detection. Neither of those additions sounds hugely groundbreaking, but as Tamasi hinted, they may just be the tip of the iceberg. We'll probably have to wait for another announcement from Microsoft to find out more.
I wonder if second generation Maxwell will support all these new DX12 hardware features or we have to wait for Volta.