Yaar I wrote a detailed post on this issue right at the time when Taliban recaptured Kabul, I won't go in detail again but would post pointwise summary.
Now please keep in mind.
- since 1979 Afghanistan is not a united country under a single Government. Soviet tried to keep it united, Mujahideen tried, Taliban tried, USA tried it and even now Taliban 2.0 are still trying but the result is still same as we know.
- Afghanistan is not a functional country since 1979.
- No one could make it a "FUNCTIONAL COUNTRY"
- all the ethnic communities in Afghanistan have proved that they can't live together under the single Government.
- We must understand that the issue we are facing at our western birders is not because of one ethnicity or the other in Afghanistan, but Afghanistan it self is the root cause of the issue.
- As long as Afghanistan remain as an State it will maintain its claim as about Durand Line which means no amount of regime change would resolve the issue. Therefore to resolve the Durand Line issue we have to resolve the Afghan in totality as the problem.
- Afghanistan is just a buffer state which remain in existence due to great game between Great Britain and Soviet Union, now Russia is no more Soviet Union and far away from our borders therefore we do not have any such compulsion or threats.
- Current political borders of Afghanistan is not serving the interest of any nation or state even the interest of Afghanistan itself. Infact it is creating issues for all of the neighboring countries and for Afghanistan as well, therefore Afghanistan with it's current borders could not remain as a country for long period, sooner or later it will disintegrate so any unplanned and sudden disintegration would have potential to hurt Pakistan's National Interests.