Valve Is Working On Another Extension To Help In Direct3D-Over-Vulkan
Not yet merged into the Vulkan repository but a short-lived public pull request on Monday as a seemingly accidental PR then quickly closed is the VK_VALVE_mutable_descriptor extension. VK_VALVE_mutable_descriptor aims to reduce the descriptor memory footprint and with its new mechanisms aims to make for "more efficient emulation of the binding model present in other graphics APIs for layering or porting purposes."
VK_VALVE_mutable_descriptor_type is through its third iteration so far and led by Valve's Joshua Ashton and Hans-Kristian Arntzen.
Those interested in the proposed VK_VALVE_mutable_descriptor_type technical intricacies in their current form can see the spec addition.
This would be the first VK_VALVE_* vendor extension merged but they in prior months have also been working on possible VK_VALVE_generic_descriptors and VK_VALVE_partial_presentation extensions too while other extensions have come in recent years for helping Direct3D and other graphics APIs better jive on top of Vulkan.