security is indeed hard. however, people building microkernels at that time were not doing it for security reasons, and it is not clear that the types of microk

security is indeed hard. however, people building microkernels at that time were not doing it for security reasons, and it is not clear that the types of microkernels they built (e.g., mach, with a huge unix "personality") had any better security properties than typical kernels. So I think it's a bit generous to look back and say "yeah tannenbaum wasn't incorrect". the hypervisor part of your argument is more reasonable - the amount of virtualization on a machine these days seems excessive, with each level solving a different problem, and a cleaner solution waiting to burst forth. I suspect, however, with new containerization and other isolation technologies, that we'll come to an answer soon enough, and Linux will still be there underneath, monolithic and all.