Without experience, land, and modern industrial farming techniques? No, "everybody" would not start subsistence farming. There would be massive famines, billions would starve and die.
But if you ignore the labour demands per mouth fed, the education needed, the amount of land to feed current western population to sustainable replacement level, the requirement to maintain advanced defence systems to prevent land being taken or otherwise destroyed, the issues with the global climate affecting whatever you do in this agrarian society, could it be done?
