What if Alexander was able to convince his men to press on into India following the battle of Hydaspis river. How will this change history? Will be Alexander be overwhelmed by the sheer number of Indian troops and killed with his men, causing an earlier collapse of his empire? Will he be assassinated so very little is changed? Will his invasion succeed, possibly leading to him remaining in power and his empire surviving? Can India be conquered at all? What's your opinion?
Alexander would have failed here. His men's morale, even if they hadn't mutinied, would be very low. While I think tactically Alexander
could win (assuming that Nanda's troops aren't nearly as numerous as the rumors, and putting stock into Dhana Nanda being as unpopular as the rumors go), it would be such a Pyrrhic victory that it would devastate any chances of him actually controlling such a vast and populated new and very foreign territory, and his men would be absolutely destroyed. And if he lost (which is a very strong possibility), than he's done. His army would be destroyed, and all the satraps would be rebelling and preparing themselves as best they can for the post-Alexander world.
If Alexander were to live, and challenge Chandragupta Maurya with a massive Iranian based army... I think that would work even better with the comparison to Napoleon's invasion of Russia, since Chandragupta is known to have used guerilla warfare, and I can definitely see him doing some scorched earth tactics, and Alexander ultimately being able to be victorious always
just out of his reach. Plus the whole
Grand Armee thing. If he can succeed in bringing Chandragupta to one pitched battle to decide the fate of Magadha, I think he wins, but it's still doubtful that he maintains Magadha in his empire long-term, and trying to keep it might just be the straw that breaks the camel's back as far as keeping the empire together goes.