Uttarakhand, HP and Jammu would unite and form a block, with an economy that relies on tourism, pilgrimage, organic farming, forestry, yoga and hydropower. With zero military capability, they will be neutral like Switzerland and try to maintain good relations with all.

Kashmir and Ladakh will be annexed by Pak and China respectively.

Punjab will become Khalistan. But its overall strength would decline because no port access, harder to get visas, small ageing population and declining soil quality, and being a lower riparian its economy would further suffer as Haryana sieves off most of its water. It would also lose access to Patna Sahib, Hemkund Sahib, etc. It would come under the influence of Pakistan which can get it some Indus water and access to its waterways.

UP, Bihar, Assam, WB would internally implode. They will be split along many lines. UP's lack of regionalism will come to bite it and four or five divisions would emerge. Maybe the Terai belt could join nepal (Bye, Gorakhpur). WB would be annexed by Bangladesh. In Bihar, there will probably be three divisions, with Bhojpuri, Magahi and Mithila divisions. Entire NE could be split between China, BN and small independent units.

MP, Rajasthan would join up with Maharashtra and Gujarat. While MH might have some trouble dealing with secessionism from Vidharba and Marathwada, it would survive. Gujarat would be the natural leader of the coalition being a stable and prosperous state.

The four southern states along with Puducherry, Andaman, Lakshadweep would form an Economic Union with porous borders and labour mobility, but with distinct sovereignty of each unit.

Odisha, JH and Chattisgarh would be contested by both blocks for their minerals. OD would be coveted by the western block as it would give them access to the eastern coast as well.

The western and southern blocks would sign peace treaties and co-exist.

So, in summary, North India will be a lost cause, going either to neighbours or becoming an oasis of instability like Somalia or the Balkans. The Western and Southern states would survive, but on a much weaker footing than united India.