Worse than before NATO got there? I can see as bad, but why worse?
First of all, anyone that's viewed as NATO sympathizers will be tortured and kill outright unless they have the power\wealth\clout to defend themselves.
Which brings us to the second reason, which is that a second civil war is coming to Afghanistan. It'll be the same teams as in the 1990s: Tajiks, Uzbeks, Persians and others in the North vs. Pashtuns in the South. They'll slug it out over who gets to control Kabul again. The difference is that this time they have an enormous amount of weapons, ammunition and ordinance, as well as the training to effectively employ it.
When we set up their Army and National Police force, we attempted to bridge the ethnic divides by sending people to different parts of the country, far away from where they were from (not unlike what many Western militaries do.) But that's totally incompatible with their culture, and over time they all migrated back towards their homes. I work in a totally Pashtun area, and all the police, border police, Army and NDS (CIA\FBI hybrid) personnel are all ethnically Pashtun. The only exception is the commander, a brigadier general in the Afghan Army, who is a Tajik. But he is rich from graft & corruption, and plans to leave for London (where his two kids live) shortly before the American withdrawal. The higher ups in Kabul have been working to allocate weapons, equipment, money and ammunition to their ethnicity of choice.
They're basically setting up their sides for the big brawl once NATO forces withdraw. It's going to be bloodier than ever.