To help clarify, since I’ve been following development for a long while.
Eevee rewrite has no ETA at all. In august it was announced that Bakker was working in other more urgent areas and that meant the Eevee rewrite being postponed, there’s no roadmap as of now.
Also, no news about meshlets or any other proprietary tech, it’s a bit futile to ask about specifics because not only Eevee is not being actively developed, is also not on the table.
I am sure you read this, but I suggest you to read it again, and take it literally and word by word. The Eevee rewrite to Vulkan does not aim to magically improve performance tenfold while adding RTX and tons of cool tech features of modern GPUs.
Right now it only aims to replace the OpenGL backend with the Vulkan backend. Period. This will make Eevee future proof and easier to be gradually implementing new features that Vulkan will make easier to implement.
As usual, and due to the open source nature of Blender, if the assigned dev is busy coding stuff that is important to make sure 3.0 gets released, and someone finds that the Eevee 3.0 is a priority, grants can be given or if you’re a coder you can try to tackle the project.
But just remember that everybody has different priorities, you may think meshlets are of utmost priority, and I may think it’s useless because you cannot implement that easily with Cycles for whatever reason (just giving an example, may be wrong about it). The Blender Foundation assigns development resources to where they see fit, and they cannot please everybody.