The A380 will last quite a while on long-haul routes with lots of passengers between busy airports. There's no other plane that allows cramming 500+ passengers into the same departure slot, and places like LAX and LHR don't have many departure slots to spare.

Emirates makes heavy use of the A380 because they are geographically forced to operate on a hub-n-spoke model. The same is true for other heavy A380 users such as Qantas, Singapore, and Korean Air. All of them fly primarily out of a small number of hubs. They simply can't do point-to-point. There are also lots of A380's flying between major cities across the Pacific, such as LAX and Seoul, Honolulu and Tokyo, etc. where there's enough demand to fill an A380 every day.