I wonder about robustness. Can the microcode physically destroy the CPU? Consider driving a bus line both high and low simultaneously from two sources. That puts transistors which ordinarily spurt out a little current to overcome capacitance into a continuous maximum current situation. Compared to maximum toggle rate in normal operation, (50% duty cycle for a transistor, exponentially decaying current when on), I’ll estimate this will easily average four times the current.

The development cycle could be littered with dead processors, but worse for Intel, if a widely used microcode has a very infrequent chip stressing flaw it will manifest as “Intel chips aren’t reliable.”