Why plan? It's working right now, alongside QSOE/N. Resources nicely partitioned: graphics controller and UFS storage for Linux; NVMe, Ethernet UART for QSOE. Please see the demonstration video.
Have you noticed that Linux on the diagram is a general-purpose OS, used for non-critical tasks? Or, refusing to watch the video, you refuse also to see what's actually depicted on the page?
> it's been working since the 01990s
What's been working since the "01990s"? What hypervisor in 1990s drove real-time OSes on industrial computers alongside general-purpose OSes, providing full resource isolation?
LinuxCNC (EMC2) was using that approach too, but at first I think they were trying to get hard-real-time performance out of Linux itself, and later I think they might have been using paravirtualization rather than full virtualization, which was conventionally considered impossible on the i386.
(QSOE/L does use seL4 as one of its possible kernels. But I guess you also haven't noticed this, because, perhaps, you don't care.)