Airbus plans on adding 100 more seats on the A380 in the future. This means more than 600 people will be riding on a single jet! (www.youtube.com) More...
Roughly, this will add about 13-14 feet of fuselage - roughly. Airbus forecasted -when developing the concept of the A380 - that air traffic in the Asian market would increase in the upcoming decades. The idea was to offer an airplane that would replace 2-4 smaller aircraft. Therefore, instead of having a handful of flights a day to a certain destination, the airline could scale that back to 1-2 flights a day. It's about getting more people onto less flights and having less air traffic. Fun little fact: the number "8" in A380 signifies the double deck. "8" was also chosen because it represents good luck and fortune in Chinese and other Asian cultures.
Some time ago, it was said, the A380 was suppose to be carrying some wheere in the area of 800 on a single flight, however, with the "fancy" interiors and "private" spaces .. I don't see how .. it could ever work.
What market? They've sold 253 planes, while the A350 and A320neo have 2000+ between them. (And that doesn't include Boeing's similar planes and sales, and coincidentally their 747-8I has sold a grand total of... 36.)