you are wrong, Kashmir will always be a part of India for various reasons
1)strategic/military --- as the India U.S relation is strong Kashmir could play a major role in maintaining power balance but it also act as a imp front for Indian army in time of war as various Pakistani cities is near to Kashmir.
2)economic---natural resources,tourism,electricity etc in other words we control your jugular veins(rivers) so in a war we don't have to fire a bullet as we control your rivers,millions of people in Pakistan would be affected by Floods and Draught without even fire a bullet.
3)yes in Kargil we made mistakes and i think that wad the last time when Pakistan could have got the Kashmir as our economy is not strong.But now we will goin to become $5 trillion economy by 2025 and a strong military power.
4)i hope you don't want to mention nukes for Kashmir unless you are on a suicide mission.