Disintegration of Pakistan will not solve the issue like militancy but it will surely serve our strategic interest in the region.The lunatics will stay there even if Pakistan is cutoff into pieces.
Pro India balochistan and sindh will not only serve our interest but will Dissolve Chinese influence and interest in the region.a pro India balochistan will cut off Chinese Path way to the gulf via karakorum and gwadar.secondly we can't really really take up the option of taking back GB in case pakistan does get separated,a forced occupation should be out of the question.Also division of Pakistan will make our entry into afghanistan lot easier and access to central asia.
Though it can't be guarenteed that the newly created countries shall remain pro India.Take bangladesh as an example for the matter,today we see may be the govt there does serve our interest but the people have turned against us,you see anti-India mind set all around.But one thing that division of Pakistan during 71 did,it prevented the third front war scenario for India.Think if Bangladesh wouldn't have separated and still would have been part of Pakistan with Pak being a Nuclear weapon possessing country,in such case it would have added upon another front of war for us.we are already facing a possible Two front war scenario,East Pakistan would have served as third front.
So division of Pakistan during 71 did us good !!But can it be Possible today ? By Military option ? - Not Possible
Division of Pakistan is only possible if the seperatist there give up to the resolution of Islamic republic of Pakistan and take up the issue of seperate nation to full throttle and bring the state into the condition of anarchy.
One thing i will like to mention which no one here brought up is the issue of "Nuclear weapons",what will Happen to the Nuclear assets post disintegration? Let's take example of Soviet union,during collapse the SU has approx over 27k deployed warheads,Most of them were deployed in present day Russia.Belarus, Ukraine, and Kazakhstan gaveup possession of nukes and the control of total stockpile went to Russia.
This should be another concern if Pakistan breakup amidst chaos !! Distribution of stockpile in such case will make Asia a heated nuclear zone.In Both the cases whether Pakistan break's up or not , the threat of Nuclear weapon will remain.the Threat will increase in case of breakup - if some rogue elements get their hands over loose nukes that will be an worst case scenario for us.
When it comes to Militancy,even if issue like Kashmir is resolved or not,those lunatics are there to stay.they will vomit their hatred for India even after break up.the hatred is not limited to Kashmir.
There are pro's and con's of such Disintegration,a strong pakistan with nuclear weapons and a state filled with anti India rogue elements will always be a threat to our existence.I Would rather prefer another break up in vicinity and a weak Pakistan