You sound angry. Why is that?
Please stop spreading misinformation. DX12 was in development years before Mantle even existed.
As for "radical", the industry used to code to the metal years ago. It was called DOS and Assembler. Was DOS "radical"? How about x86 assembler?
On Windows DX12 will gain about as much traction as PhysX did, Vulkan even less so. Generally speaking only the biggest AAA engine houses will be able to afford the resources to properly code for DX12. Windows has thousands of games released for it every year, including huge numbers of indie games written using garbage-collected C#/.NET. The industry has been moving away from low level APIs for years.
Even if we take what we have so far, about half of DX12 games have been a shocking failure, running slower and/or buggier than DX11. The mantra "things will get better" doesn't hold given the hardware is ever changing, and DX12 paths will need constant app-side patching to maintain performance advantages for new hardware. Almost every single Mantle game now runs slower than DX11 on newer AMD hardware, yet it's quietly swept under the rug.