I am seeing forward to a possible "WebVulkan" analog to WebGL.
Due to the refinement of the pipeline and memory access, etc. provided by Vulkan, there's a lot of room for optimization.
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Though on the other hand, even with additional overhead on a Vulkan web API, the improved state management and access to command buffers may still allow for smarter rendering with negligible overhead via JS
Fun times
On the other hand the nature of implementation in Chrome, i.e. does seem to lend itself somewhat to a command buffer approach as in Vulkan.