Windy, possibility of Pakistan splitting is more than India. When Khalistan in 1980's could not split, nothing can split India anymore.
1947 was a mutual agreement when there were 1000 of princely state. Now there is no British Rule to arbitrate.
Post 1947, size of India has grown ( Goa, Sikkim) while that of Pakistan got half.
As a third person, where will you put your money?
And yes, Indian Constitution will remain same. All that Alaap of RSS, NAZI, ZANOCIDE, EXTREMISM by PMIK is just scaremongering and propoganda. So lets not go there.