Well, the situation is changing quickly. Pakistan used to be very pro-Saudi and it didn't have good ties with Iran, now it's changing very fast I think. Pakistan and Iran are establishing amicable ties based on common interests, neighborhood and brotherhood and mutual respect. Pakistan is realizing that Iran too can be a partner beside Saudi Arabia and because they have good ties with Saudi Arabia it doesn't mean they don't need Iran. So it's very probable that Pakistan will sacrifice the Taliban for a better option that Iran agrees with. Iran has much more to offer to Pakistan than the Taliban and Afghanistan has. If they choose Iran and drop the Taliban, they could use Iran's natural influence in Afghanistan in a positive way, they could increase trade with Iran and many other benefits. Moreover, I'm sure many the people of Afghanistan don't want the Taliban any more, They just want the USA to get kicked out of Afghanistan, but they don't want the Taliban either and I'm sure Pakistan knows that well.
What makes it difficult for them to choose a better option?