The Life of Christ by Ven. Fulton Sheen - Chapter 58: The Divine Mandate

"If this commission were given solely for the time span of the Apostles, it is evident that they could not possibly go to all nations. The dynamism or current that was passed into the Apostles under the headship of Peter was to continue until Christ’s Second Coming. No doubt was left concerning the authority and the work of the Church when the Master would leave the earth."