Vulkan 1.0.42 brought many new features for this update debuted at GDC17 and the Vulkan 1.0.43 update since added two more extensions, but there still is longer-term planning going on for additions to Vulkan in the future.
Some of the possible "future directions" discussed by Piers Daniell fits into the areas of shader functionality, WSI (windowing system integration), and other areas.
When it comes to advancing Vulkan's shader capabilities, there is areas to advance Vulkan's compute capabilities with "richer compute algorithms", improved compute performance, and more tightly-defined behavior. Also on the shader front there are areas for improvement around HLSL (Direct3D's High-Level Shading Language) support. Also of interest is in expanded subgroup operations.
On the windowing system integration front, possible future Vulkan improvements are around shared presentable images, allowing partial updates of presentable images, a dedicated memory option for individual buffers and images, improved Windows full-screen support, Windows memory residency control, and expanded surface/display capability queries.
There is also the likelihood of having a VK_KHR_maintenance2 extension for viewing compressed image formats and other additions.
Learn more about Vulkan at one year of age via the PDF slides or the video recording embedded above.