I think, Lufthansa will return to PHX
eventually, whether the new US Airways will remain in the Star Alliance or not. Phoenix is a thriving city, and it will continue to grow. At some stage the local O&D traffic alone will be sufficient to warrant nonstop service from Lufthansa's FRA
hub. Just because LH
pulled out does not mean that they don't monitor the development there anymore. Philly also lost LH
service a long time ago, and years later it was reinstated.
I would also expect US Airways to launch a few transoceanic routes in a few years from now, in addition to the new Hawai'i service, which has been announced already.