Microkernels wouldn't really help. The point of a microkernel is to drastically reduce the coupling between parts of a system. Current hardware has far more coupling between parts. For example power management requires coupling (consider a NIC on a USB controller on a PCIe bus) where all pieces need to pull together. Or consider something like scheduling in a world where processor cores aren't identical and what runs where matters.

Your microkernel would either perform way worse (eg worse power consumption), or have pieces so tightly coupled that you'll wonder if it was worth it.