Plus, better isolation between driver code and other kernel code (which Fuchsia seems to bring; correct me if I'm wrong) would be good for everyone, since you can be relatively assured that running vendor-provided driver blobs is safe.
"Isolation" of driver code that can talk to on-SoC hardware is just not very meaningful. You can only have real driver isolation if it's enforced on the hardware side via some IOMMU mechanism (or by keeping the hardware isolated on the USB bus, etc.), otherwise you're just adding pointless overhead for no real benefit.
It's desirable, but typically hardware devices have DMA-capable buses that can read / write to arbitrary physical memory. So a buggy or malicious WiFi driver may be able to use the WiFi DMA hardware to write into the GPU driver's memory, and no pure software mechanism can stop it from doing so.
IOMMUs solve this problem by giving hardware devices their own virtual address spaces.
