The 380 makes a lot of sense in heavily congested air corridors. Anywhere in China, Japan, SE Asia...You'd think that, but the Asian carriers who've bought A380s are still mostly using them on their long-haul routes.
This is a lesson Boeing has learned twice now: once with the 747SP, and again with the proposed 787-3. Both were designed as specialized aircraft to bring efficiency to slightly shorter high-density routes. But the 747SP only had a production run of 45 aircraft, and the 787-3 was cancelled due to lack of interest. The 787-8, on the other hand, has been doing well in Asia, and several low-cost carriers fly them now.
The A380 is an even worse fit because it requires upgrading the airport infrastructure, which either won't happen or won't happen soon enough on some of the highest-density routes (as the article notes, Mumbai couldn't handle A380s until very recently).
Boeing seems to be sensitive to this with their planned folding wingtip on the 777X family, designed to guarantee that airports which can handle current 777s will be able to handle the larger 777X. It'll be interesting to see if that pans out.
