Well this takes into account a few issues. Firstly have the Military and the ISI kept solid links with these elements. If you read the Western Media we all sleep in the same house and share breakfast. If that is the case we should have no problems with the Taliban as we are already in league with them.
Then comes the issue if we are not in league with them and while we are fighting them, the US and Karzai are busy trying to appease them. That may actually explain where the hell these Taliban are getting so much money to buy RDX and TNT or specifically getting the supplies needed for the suicide bombings.
However if th Taliban do come to power in Afghanistan it provides our military with much needed strategic depth. However lets not discount the India or US factors either. They do not want to see a stable Pakistan. So if the Taliban do come into some form of coalition, it would not be to our advantage.
Additionally we must see how much interlinkages tehre are between those in Pakistan and those fighting Afghanistan.
Frankly if this does happen, we would need to move in fast. We need to move in and establish schools right off the bat teaching the people in Pakhtunkwa a less crazy version of life.