Seems a good step, but I also cant help but feel this will mean more stuff moving over to VRAM making it even more scarce.
That's the opposite of what this does. It's designed for that situation, mostly because of the Xbox series S.
Simultaneous access is a latency benefit, since it's been accesible from the CPU and GPU for a while now (at least in DX12/vulkan)
Old (DX9) setup:
Compressed Storage -> RAM -> CPU changes things as requested -> Duplicate to VRAM -> GPU processes 3D goodness
Newer DirectStorage (when it eventually gets used correctly)
NVME storage -> VRAM, GPU harddware decompresses (Compressed NVME -> VRAM)
VRAM is now accessible by the CPU and GPU for either to read/write to as needed. No redundant "flush the whole thing and try again" steps
"Hey CPU can you hash this file and verify it's the one we need already decompressed and avoid loading the whole thing from scratch again? Cheers"
Consoles have shared RAM and VRAM, so this is primarily for them.
On PC it just means game engines will use less RAM, it does not mean they're going to use more VRAM.