In 330 BC, there was a plot against Alexander's life lead by Dimnos, a Macedonian of Chalastra, for reasons somewhat obscure, but what Diodorus says was because Dimnos, "found fault" in something Alexander did. Either way, it isn't relevant, because the conspirators will be torn to pieces once it is over, despite the army's reservations about Alexander's adoption of Achaemenid customs and purging of the old guard, many still loved their king, and probably would not take kindly to this. This was the same plot used as an excuse for both Philotas and Parmenion to be purged. So what if, somehow, through prodigious luck, the plot was not revealed, and Alexander was killed. A main difference from other scenarios is that the Achaemenids have already been decisively defeated at Gaugamela, and after that, the core of the Achaemenid empire was taken and the unconquered parts reverted to a loose alliance of satraps and chiefs. Still, Bessus remains a threat, deep in Central Asia and Bactria, claiming the title of Shahanshah as Artaxerxes V. Also, Alexander IV isn't born yet, Alexander is unmarried, and there is only Philip Arrhidaeus, far away in Macedon. How would the army react? How would they try to put things together? Who becomes regent? How do they deal with the Persian remnants? Do the generals cooperate, or does the empire split?