I don't think that full access to all memory and SUBLEQ architecture must happen at the same time. For instance, you can already run a 100% ring-0 operating sys

I don't think that full access to all memory and SUBLEQ architecture must happen at the same time. For instance, you can already run a 100% ring-0 operating system on top of x86_64 (e.g. DOS, TempleOS, Mezzano), but it should also be possible to equip a SUBLEQ CPU with some kind of programmable MMU with memory protection that will cause segfaults to happen when invalid addresses are accessed. (And then you'll need syscalls to actually jump to the proper ring and access that memory, and such stuff, which might go against the political agenda of DawnOS.)