Consider this
http://gc.kls2.com/cgi-bin/gc?PATH=&...OR=&MAP-STYLE=

Where are the routes which QF could not easily fly with 747-400 non-ER and with world fleet of just 6 747-400ER, but which make sense with the range of A380-800? Note that QF has less payload than any other A380 operator (QF 450 seats, SQ 471, EK 489).

SYD-EZE is 11 789 km. SYD-LAX is 12 051 km. In the other direction, SYD-DXB is 12 039 km, and shall soon be flown by A380 - that of EK.

South Africa is already closer than 11 500 km. The next 2000 km are in Central and Eastern Africa, with few interesting big destinations. SYD-SDA (13 400 km) is hardly interesting, either. Nor is western Siberia.

In Western US, beyond LAX and SFO, there are few big destinations that are not better reached by connecting in west coast gateways. SYD-PHX (12 550 km), SYD-SLC (12 897 km), SYD-DEN (13 435 km) sound like minor, point-to-point points. SYD-ORD at 14 857 km, gets hard without A380-800R (which Qantas may well get if and when Airbus bothers to offer it).

But SYD-MEX (12 984 km) and SYD-GRU (13 387 km) look like major destinations reachable by A380.