It seems to me that when a king comes to power, the Knesset will not be disbanded; neither will the institution of elections be discontinued. The government will not lose its importance. There will still be a need to run the state as we know it today.
What gives the Rabbis the right to add laws to those which the Torah commanded us? From where do they derive the authority to enact preventative safeguards that result in the uprooting of Torah law?