Bringing the Joshua Tree Tour out for AustralAsia is probably a way for U2 to not have to continue touring beyond these continents.
If they go out with a completely new tour and setup they might feel fans around the world would want them to bring it back to Europe and the US,
this is merely housekeeping and fulfillment of a promise to come back to Australia bookending the 2017 tour.
Although I was hoping for the tour to come, I can’t believe that this will happen now ..I still remember how it felt when Bono said in Berlin that they are going away now (and it was meant to be for the Northern Hemisphere).
I“m beyond excited