if the state suddenly decides that it will not use violence, and if it suddenly decides that it will not use any mind-control methods except pure reason, wouldn't it then cease to exist?

according to Hobbes it essetially would. his arguement for the state was that "in a state of nature" we are all egoists. and a particulare egoist or group of egoists, the "soveriegn" will take controll useing "froce" and manipulation, in order to maintain power, the other egoists then accept this, becuase they believe that the soveriegn is neccesary to prevent the "brutish" state of nature that would exit withought. why Hobbes felt that society was seprate from nature, is beyond me.
why people would take the word of someone who openly uses manipulation, for that matter, is also far beyond me. but all that aside, withought manipulation and force the state has absolutly no reall power, ad ould still exist and simply continue its reign based on other forms of controll. for example ecconomic domination. the corpratocracy currently runs the show, and true they use manipulation and force just as the state does but they also use private property, specialization, and a monopoly over rescources to maintain controll, so the only real way people will be able to free themselfs from usurption is to ride themselfs of capitalism before riding itself from the state, especialy since in or modern age the state is the corpritocracys's plaything.