You would really have to divide this up among several players and sub-divide that by long and short term objectives...

Tribal folks - might long term enjoy having a Pashtun-stan, but only as a tribal federation

Taliban folks - might settle for a Pashtun-stan, but only as lesser outcome. Why settle for a sliver of area when you used to rule a country. Besides their style is a little too directive for tastes of mountain tribals. So Taliban and Tribal folks outlooks not really the same.

AQ folks - They don't need a constituted state, ungoverned areas are far more conducive to what they need now. A Pashtun-stan would have no big-daddy if they hosted terrorist training camps.

In light of all that, I don't see this great confluence of interests - long term.

Of course I'm dated in my understanding of the tribes and their affiliation/interests. As we could see in Iraq, those can change quickly.