Doesn't APS takes care of most of the ATGM threats?
Yes, they do but they have their limits. For example,
1. Any system can be overwhelmed....................eventually, if the enemy throws enough numbers of ATGWs at your way.
2. What if the sensor gets damaged by artillery fire or some other means??
There are some other issues but that's for another time.
Maybe not in urban areas.
Exactly. Personally, I would not want to send in an armored unit into an enemy-occupied heavily built-up area but sometimes, there is no choice and if your AFVs are not adequately protected, you'll have the devil to pay, metaphorically speaking.
You have almost managed to convince me. A case for a T-15 style ICV, that extends ATGM protection to passive armour, can be made for Punjab theater where there is high density of built-up urban and semi-built-up rural areas, especially around and approaching Lahore. The Indian Army doctrine (Cold Start) also involves a tactic that calls for Indian Armoured Columns to move close to Pakistani civilian population centers (hugging the Pakistani cities) because it negates Pakistani nuclear threats, unless the Pakistanis plan to nuke the edges of its own cities just to get rid of a few Indian tanks. In this case the Indian ICV should have passive armour to survive against ATGM. So yeah, you are right. There is a case for T-15 style ICV in Indian Army.
You're on the right track. That was indeed the line of thinking I had based my arguments on.
In Thar and Himalayas, its still better to stick with a <30-ton ICV.
Yeah, even though I would still prefer a heavier AFV even in those theaters but I believe we can get away with a lighter less protected vehicle just fine in such open terrain conditions.
It appears that the army has decided to take the one-size-fits-all approach when it comes to selecting its next IFV but I'm not at all sure if that's the practical option given the uniqueness of our predicament. I think two different versions of IFVs should be designed along with an MBT, an ARV, an AEV and an urban tank support vehicle using the same basic hull design to ensure maximum commonality among them.