The Taliban will remain a threat until they are driven out from everywhere they have any refuge. That means attacking them in every place they are active, especially where they are based. It will be a long and protracted war, but the bottom line is you cannot leave any area for the to assemble or train.
They will certainly not be able to destroy them if they leave an area for them to retreat too. It doesnt make sense. You cannot treat a cancer unless you remove it from everywhere.