Alandowner validly conveyed a small office building to the green party "as long as they use it for operating quarters until the next presidential election." after the next presidential election, which was in three years, the building would go to a private organization that monitors and prepares comprehensive listings of gas prices throughout the country. a year after the conveyance, the landowner died, validly devising all of her property to her son. although this jurisdiction is a common law jurisdiction with respect to all real property considerations, the state's probate laws provide that future interests or estates in real property may be passed by will or descent in the same manner as present or possessory interests. last week, the green party and the gas monitoring organization joined together to sell the office building in fee simple absolute to a developer. the son filed suit to prevent the sale of the property to the developer. in this action, who should prevail?