Sometime Today, A cobbled together some glyphs to say:
I believe, some of those things are possible with the Hurd. One can use two independent kernels at the same time.
They'd run as services within the HURD microkernel. Almost, but not the same thing. There's a very tiny difference in that, with the hurd, you get a scheduler. With two kernels running on their own, how do you handle that?