Just hours before King Juan Carlos made his historic TV/Radio Broadcast ordering the Military to stand down and return to their barracks thus ending any chance for the Fascist to regain power, the King had a a phone conversation with his father, the Count of Barcelona. In that conversation, the old pretender encouraged his son to "Show them you got balls Juanito!" As a result, the King stuck his neck out on the line, risking his throne, his dynasties return and that of the monarchy, and what might have been the last chance for democracy to set a foundation in Spain.
The king warned the fragile democratic Cortes and Constitution that they had to grow strong and show it could survive on its own and not have to count on him to save its butt if another revolt occurred. In other words,, "My family waited many years to regain the crown, and I plan on staying with or without democracy." I do not know who would have won in another Spanish Civil War. I know all of Spain would have lost.