Alexander may expand his empire more to the east, but he may lost his lands in the west. Transportation and communication is bad in that time, it is hard to control an large empire at the time. Chou Empire in China creates fiefdoms is to lubricates the civil administrative system, because at the time, highly centralized government can't control local governments effectively, but through this system (so called feudal system), they will pay the price of fiefdoms will rebel someday. So, when Alexander expand his empire more to the east, there will be high probability that his generals in the west launch an open revolt against Alexander and split his empire up, but Alexander can do nothing but watch.

Alexander's Hellenistic Empire falls because his lands is too large to maintain a centralized government to rule over these lands, so it split into many diadochis... Roman Empire falls because it is too large to maintain a centralized government in Rome, end up with prefectural governments secede from Roman Empire unitarily and difficulties on transporting armies... Alexander' Hellenistic Empire may expand to China if he don't die young... end up Egypt taken over by Nubians and Balkan taken over by Peleponesian rebels.

Alexander is called Iskandar in Arabic. But Iskandar Zulkarnain defitnetely not the Alexander of Macedon.