It is already almost uninhabitable and has been for a long time. Nevertheless ~10M people live there. Technology is solving this, either the root cause or the symptoms
Air conditioning the outside is almost assuredly not sustainable.
Not sure what you mean “the outside”. Only indoors are air-conditioned (using electricity). And in the UAE, right now, electricity generation is slowly being switched over solar energy (away from natural gas), which is clean / renewable / sustainable. (https://www.greentechmedia.com/articles/read/worlds-largest-...)