You will be surprised to learn what I think will happen.
Before the next elections in 2024, India will change the constitution to make this a Presidential form of democracy. It will be Modi against anyone else, and he will win hands down.
States will no longer be states, but provinces, with the Center holding more power over revenue and other affairs, to keep states like TN, Kerala, WB in check.
Many Pakistanis are under the illusion that India will have a civil war etc etc. Naay....what will happen is when the BJP changes the Center/State relationship, southern states like TN/AP/Telengana/Kerala/Karn will rebel in some way. They are already tired of subsidizing the cow belt. That will only intensify when the Center demands more of their revenue.
The idea of India as a nation-state will not be demolished by Muslims, or Dalits or Pakistan, but by the Southern states, and I predict that the Tamilians will take the lead on that.
Before anyone jumps on me and thinks this will happen within the next 3-5 years....naah.....it will take longer than that 25-50 years.