The current Afghan state has more legitimacy and more capability than any of its opponents. But may have major money issues if foreign support dries up.
The only way they can be defeated is if Western powers (aka US) has decided it is a better bet to have a Pakistan-run militia in power in Afghanistan (or if the US has decided a division of Afghanistan is somehow in their interest).
The US has that kind of leverage because it leads the support effort. Russia and Iran and India can support the Northern alliance but probably wont pay for the whole place.
Minus that kind of US treachery (no other word for it), this state will survive.
Bets?