If something like the Taliban and Al Qaeda exist I imagine conflict with them and India would naturally form. Taliban would dislike heavy amount of Indian influence in the country. Taliban aren’t internationals like Al Qaeda. They are more nationalist and probably won’t like India involving themselves in their affairs. They might commit raids and terrorist attacks around the Indian border or clash with any military presence within Afghanistan. Al Qaeda and other extremist might just see India as a Hindu power who is occupying Muslims lands and people. Then being friendly with Israel and the US would only encourage more dislike by extremist. Furthermore, if this India is a superpower it can use its diasporas in the gulf to influence Arabian nations that in some cases are now majority Indian. Some Arabs might see all these Indians in Arab countries as India being imperialist and colonizers. People like Bin Lidan would take advantage and stir up hate. Al Qaeda uses Afghanistan as a base to commit attacks against India which India might respond with bombing campaigns and special force operations on terrorist bases at first. I’m not saying the Iran border will be unstable. I’m saying I see them being hostile towards each other. Maybe taking the place of the Pakistan and India conflicts of otl. Basically, they would have a border that is heavily militarized and guarded on both sides. India could still develop nukes as a response to China. Iran now is hostile towards the only two nuclear powers in the region. Maybe 3 if you count the USSR and how they develop in this pod. Iran nuclear program probably gets condemned just as much internationally but receive more support internally due to them neighboring two nuclear powers and a third very hostile nuclear power within launching distance. I don’t see a united India impacting the reasons for revolution in Iran too much and honestly I think it makes the situation more interesting. Also I feel like if they use special forces or use their law enforcement to strike and take down drug lords and opium fields within Afghanistan some locals will get resentful. Afghanistan seems to dislike any foreign presence no matter the reason they are there. Additionally, India could use drug lords as a political tool like the US did in Latin America. I’m not sure how bad drug use is in India but I know it is a issue in Iran especially heroin. Drug lords often come into conflict with religious hardliners and communist due to them both often being against drug trafficking and punishing it in extreme ways. India can use these people to fight communist in the Cold War or later on religious extremist. Drug lords have power, guns, and money that India can use against who they consider bigger issues.
The situation at the borders will likely impact demographics in Northern India and Pakistan in a united India. The border area where Afghanistan, India and Iran could be a drug trafficking triangle. Like otl you could have partisans and terrorist active in the area. You also have some tribes and ethnic groups that think they can just go back and forth across borders. I imagine a united India is a superpower by the 2000s so many Afghans might immigrate to India. Does any one have a more detailed information about how India population would develop in the north if united and considering what I mentioned above? Also how many Shia are in Pakistan and India? Would a theocratic Iran fund unrest among Shia in India while groups in Afghanistan fund Sunni unrest in India? These conflicts could lead to displacements of people and immigration from the area so I am more trying to figure that out to get a idea about the possible demographics of the area