Yeah nice to hear that maybe in time they may become close enough to have a free trade area and customs union or with a stretch a monetary union. Without the horror of partition a close relationship like USA and Canada is almost inevitable followed by a similar initial hiccup. Of all the countries I see Bengal will have some trouble with minorities if it includes Assam. But as until recently the entire northeast used the Bengali script so Bengalification of the northeast with a hybrid identity including Assam is probably possible. India would have very small religious minorities and a course very similar to today can be adopted. Pakistan would be having a large Hindu and Sikh minority( I am assuming that the provinces wouldn't be partitioned as the chances of bloodbath increases dramatically) and a massive Punjabi dominance more so than OTL.
One thing that I am wondering is the military. Punjabis formed the bulk of the military at 65% followed by Gurkhas at 15% . India and Bengal more so would lack locally recruited militaries so they would probably have to make a military from the scratch due to that idiotic martial races scheme.
More importantly India would need a nee Capital city as Delhi would be right on the border with Pakistan if Pakistan gets all of Punjab then Delhi is a boder town. The New capital can be Lucknow (if the North is preferred), Nagpur or Jabalpur (if a central location is sought or Mumbai (the largest city in India).
According to me it would be quite hard in India. In Pakistan some of the states could theoretically survive like Bahawalpur, Patiala but not Kashmir Kalat and the Baloch states can be reformed too. The smaller Punjab states can form something like the former Indian State of
PEPSU an so can the small states on Kashmir border be reorganized. Many Muslim princes being part of the Muslim League also helps in their acceptance.
In Bengal(including Assam) we have 3 princely states Manipur, whose boundaries are quite reasonable with a proper ethnic and linguistic majority would be allowed easily, maybe make them adopt democratic reforms like the OTL 1947
constitution before they joined India in 1949, the other two Tripura and Cooch Behar were district sized separate units and there would not be much of an issue with them being around. Bengal being a progressive state may make or coerce them to adopt democratic systems and they can keep existing like Yogyakarta in Indonesia, maybe with a bit more identity. Bengal inherits the dominance over Sikkim too ITTL.
India would have a lot of trouble keeping up the Princely States. The bulk of them would fall in India some as small as an estate, poorer than an average zamindar. Gujarat would need a thorough reorganization as the hundreds of States there is a complete mess. Only some states can survive economically. The contempt the Congress had for the Princely States makes their survival more difficult. Hyderabad would be on crosshairs since day one with its feudal system and suppression of Hindus being intolerable. If nothing is done we see an earlier revolution in Hyderabad like
this one. Mysore and Travancore can survive as they were doing quite well and were seen as role models of governance so they can continue to exist. Central India and Orissa are dotted with unviable Princely State, my money would be that they would be mopped up with pensions being provided to the former Princes. Rajputana states can probably be organized into a PEPSU like state.
Speaking so much about Princely states. In your Indian election parts I didn't notice seats for the Princely States. Did ITTL the British made them allow political parties to contest elections democratically rather than undemocratic nominations they practiced OTL?
The Asafi Jahi would be glad if they are allowed to survive. Their rule of Hyderabad resembled feudal ages and they would be the prime target for the Indian Government and would be forced to reform or perish. Their rule was the worst in India surpassed only by Kashmir. Their cities were quite modern like the rest of the country but the moment you enter the countryside you go back 300 years of social evolution.
Indians could make VCOs(Viceroy's Commissioned Officers) since the beginning of the British rule, actually the VCO corps was nearly entirely Indian for the Indian units. The VCOs were the NCOs(Non Commissioned Officers) of the British Indian Army. The Indianisation process of the armed forces OTL allowed Indians to become full commissioned officers and those Indian trained in India(Indian Military Academy in Dehradun) were called ICOs(Indian Commissioned Officers) who were allowed to command all Indian Army units including Europeans and those(everyone including Indians) trained in Royal Military Academy in Sandhurst were called KCOs(King's Commissioned Officers) any unit across the empire. Indianisation was the process to allow Indians to command all Indians upto the Brigade level although they could command europeans attached to their units too. So what is being done ITTL?
As India, Pakistan and Bengal are becoming Dominions would the Empire be abolished and the Monarch become the King of these three realms or would the title of Emperor continue? If the Emperor becomes the King in these three realms then the Governor-General loses the additional title of Viceroy along with it.
If Germany avenged themselves by beating France and bombing Britain in the Second World War then the Soviets also avenged the defeat of Russia in the First World War from Germany.
It's a pity that Serbia didn't start the Great War ITTL and they were on the wrong side of the war they did start.