I've long thought about these kind of OS designs, and what great features they can enable (such as time travel debugging). But the non-determinism introduced by inter-CPU interactions is a fundamental limitation, hence the need to run everything on a single isolated core.

One day(^TM) I'm really keen to design a multi-core CPU architecture that allows for deterministic message passing between cores in such a way that you could get this kind of software working with true parallelism.