You might find this interesting - https://en.wikipedia.org/wiki/ETOPS - That's part of what's changed the hub-and-spoke model of the past since twin-engine planes can now go much further from an emergency landing.
http://www.gcmap.com/mapui?P=jfk-syd&MS=wls&DU=mi&E=330
Try dropping the ETOPS to 60 minutes and you'll be able to clearly see where the airports are.