I heard an expert say that one of the A380's weaknesses is that it only comes in a passenger version, not a cargo one like the B747 does. The cargo version of the B747 makes its market wider. One more weakness of very large jumbo jets (A380 and B747) is that, nowadays, most flights fly directly to the destination (point-to-point), not hub-to-hub as in the 1970s. The point-to-point model causes airlines to make more frequent flights with smaller aircraft. In my country, even small airports are now international airports. Two neighbouring cities in neighbouring countries have small propeller aircraft flying directly between them, without having to go through the main airport in one country's capital city. This makes it very clear that very large jumbo jets are no longer required for passenger service.
On the other hand, the demand for air cargo has never been greater. Trade over the globe has to be quicker. This means that large jumbo jets are needed in cargo service, and - to allow easy centralization of cargo-handling equipment and personnel - it's generally preferable for these freighters to operate to and from the largest, most central airports in a country.
The question is, is it possible to convert an A380 for cargo service when there is no longer a market for the passenger version?