Big problem out of PHX will be the high temperatures. That forces a reduction in CLB limited performance which reduces fuel or payload capability. That might restrict PHX to 'near' Asia cities (Tokyo, Seoul, Bejing?).

For the 777-200 PHX needs longer runways for very long haul flights. 787 in DFW appears fairly evenly split between CLB and RWY limited on a 10,600' runway up to about 95F. Above about 95F in PHX would reduce the 787-8's CLB limited performance. So news of a runway extension might be good news for potential 777-200 flying. 787 might not need the runway extension due to the CLB limit being the limiting factor.

Altitude is the killer for Jo-burg to the U.S. flights. 5000'+ kills the single engine climb limited performance which causes significant payload restrictions. It will be limited to about 465-470K lbs even in cold temperatures vs. a 502K MTOW.

Boeing performance charts show 'high engine thrust' charts. Maybe that's a solution to reduce the temperature problems in PHX and the altitude problems in Jo'Burg.