That is a good question, since it would only take a very small percentage of the population of Kabul fighting back to make the Taliban occupation impossible. If 1 man in ten from Kabul decided to fight back the Taliban would face 180,000 defenders. That pretty much eliminates the ability to ride or walk around the streets.
It may be that urban populations in Afghanistan are like urban liberal populations here. Does anybody think that the urban liberal elites in America would personally fight for their values and beliefs?
They probably will start fighting once the dust settles. As they did before, regional warlords will organize and gain followers, and start fighting with the Taliban. What did the warlords do before to fund their men and weapons? Remember Ahmed Shah Massood and the Northern Alliance?