The state is simple an aggregate of individuals, not an organism in its own right. Regardless of laws and constitution, its actions will always be contaminated by the beliefs and practices of the citizens. By way of example, if BJP comes to power, encounters of suspected terrorists will be more kosher than what is now. You may not be aware, but very large sections of bureaucracy, the police and the forces are strongly pro-Hindu and this places a practical limit on state's flexibility of action. Can any government dare to give reservations to Minorities?? Or to openly declare beef selling legal in any north Indian state?
The point I am making again is that the secular shell will remain as there is no advantage in shedding it. But the body politic, in reality, will become more pro-Hindu as time goes by.