A related idea occurred to us recently, after seeing the VROC "dongle".
There may be a way for Microsoft to modify future Windows OS
to boot from an OS "software RAID" e.g. by permitting the
STARTUP files to be pre-loaded on a USB thumb drive.
If this were done in a generic way, it would overcome the
published restrictions of that VROC dongle solution.
At the risk of repeating myself too often, full x16 PCIe slots
do not suffer from the MAX HEADROOM imposed by
Intel's DMI 3.0 link, assuming motherboard chipsets
assign full x16 logical lanes.
And, if multiple x16 add-in cards can support most modern
RAID modes, making those RAID arrays bootable
is progress just waiting to happen e.g. Highpoint SSD7110.
Lastly, these developments will dovetail perfectly
with PCIe 4.0, which will oscillate at 16GHz.