The solution is indeed only war.
Alternatively, a total economic collapse of India will also work but that is unlikely at the moment.
That solution of war attempted several times. Only once was an independent state formed due to an Indo Pak war. That was 1971 when India carved Bangladesh out of Pakistan.
I am not trying to diminish your zeal for a solution to Kashmir. Even though my loyalty is with India, I wholeheartedly feel for the Kashmiri people.
But my friend, war is never a solution to such matters. The amount of bloodshed that we are talking about is unimaginable, on all sides.
Despite the poverty and internal political divisions within India, one thing that India has demonstrated very well is its ability to stay united against any and all outside challenges to its sovereignty. Never have illusions that the minorities of India will support any outside forces. And that absolutely includes our Muslim brothers in India. Regardless of what you may see or believe, a few exceptions notwithstanding, Indian Muslims are an extremely patriotic people.
Also, the Indian Military is not unprofessional or weak, as most Pakistani friends believe. Remember that statement that President Obama once made...wherein he stated that the India US partnership has the potential to become the defining partnership of this century. He went on to say that there is a reason why the highest number of joint military exercises that the US military has is not with the UK or Israel, but with India.
My point is that both Pakistan and India have very capable militaries (even though most Pakistanis believe that India has a very weak Army, Navy and Airforce, that will possibly roll over and surrender in a day or two, atleast that is the impression I get from our Pakistan friends in various online forums), and any military misadventure would be just that - a misadventure.
In my opinion, the only long term solution to the Kashmir issue, is great economic cooperation between India and Pakistan, so that both countries reap the benefits of enormous progress of the subcontinent. Say fifty years down the road, both India and Pakistan would be one of the most vibrant economies of the world. Not only India, both Kashmirs shall be prosperous, with people of Kashmir having solid employment/industries and educational/research institutions. Instead of having cross border terror we should have cross border free trade that benefits and uplifts everyone on all sides.
As I imagine and look far into that beautiful future, I see a wonderful Indo Pak economic union where borders become virtually like US/Canada, and India/Pak including Kashmir becomes one great economic union. When the aspirations of all people are met, division will disappear and we will all live a harmonious life (atleast our future generations will).
One can at least dream.