The production of the Boeing 747 passenger variant, known as the 747-8, effectively ceased in 2021. There were a few reasons that led to the discontinuation of the 747 for passenger flights:

1. Evolving Market Demand: The market demand for very large four-engine aircraft like the 747 has decreased over time. Airlines have shown a preference for smaller, more fuel-efficient twin-engine aircraft that offer greater operational flexibility and lower operating costs.
2. Advances in Technology: Advancements in aircraft technology have led to the development of more fuel-efficient and cost-effective twin-engine aircraft, such as the Boeing 777 and the Airbus A350. These newer aircraft can offer comparable or even superior performance on long-haul routes while consuming less fuel.
3. Changing Airline Strategies: Airlines have shifted their focus to point-to-point operations rather than relying on large hub-and-spoke models. This has increased the demand for smaller aircraft that can connect secondary cities directly, rather than relying on larger aircraft to transport passengers to major hubs.

As for a replacement on long-haul flights, the Boeing 777X and the Airbus A350 are among the leading contenders. These twin-engine aircraft offer increased fuel efficiency, longer range capabilities, and improved passenger comfort. They have become popular choices for airlines operating long-haul routes and are gradually replacing older aircraft like the 747.

It’s worth noting that Boeing will continue producing the 747-8 for cargo operations, as there is still demand for large freighter aircraft that can carry oversized cargo and serve specialized markets.