If there's one thing we should learn from history, it's that the Taliban will wreak havoc again if they're allowed to take over Afghanistan after the US withdrawal. Yet our leaders claim to have won a major victory after US and Taliban delegations met in Qatar and the US agreed to withdraw its troops in eighteen months. Shah Mahmood Qureishi chortled like a kid who's just been given a ton of chocolates, crowing at the "success" of his foreign policy. The truth is, as the Taliban said after the talks, nothing has been decided yet. 
But if, God forbid, the Taliban are allowed to rule over Afghanistan again, it will be bad for the whole world, particularly Pakistan. We'll see a flood of refugees pouring into the country, unveiled Afghan women will be killed for appearing in public, and all those who were part of the current government or supported it will be executed. Drugs and weapons will flood Pakistani markets, wreaking havoc with our economy.
If there's one thing that should cheer our hearts, it's that India has lost much face. It has invested billions to help Afghanistan, but if the rebels win, they will boot all Indians out of the country.
The only solution is that troops from Muslim countries should be allowed to keep the peace in Afghanistan after the US withdrawal. But that will not be acceptable to the rebels.
Whatever happens, we're headed towards many more years of turmoil.