And now, the B747 is being laid to rest as a passenger aircraft, relegated to the fleets of cargo carriers.
I wouldn't count it out yet. Boeing has received orders for 747-8Is in the last couple of years because there are still routes where the aircraft works better than an A330neo or 777/777X. I think we may see another wave in the next 2-3 years as well as there are already A380 operators looking to replace the aircraft as the economics of the airplane just haven't worked out, but they need the seats.
The 748 has 20 unfilled orders at the moment, all for the freighter version.
Both the A380 and 748 were products of the pre-crash economy, when there still was a perceived demand for very high capacity aircraft, especially in emerging markets. But decreased demand, better engine tech, longer range and subsequently higher ETOPS ratings (240 or 330) basically killed both aircraft. Like the trijet before, the quadjet is dead.