@Setanta,
I suspect that, if the analysis I hear was correct, and it gave lots of quotes from the WH supporting the hypothesis, that it's more about recognizing that Afghanistan is a tribal society, where various tribes will always vie for power, and that a stable and nicely democratic gov'mint isn't a viable exit strategy.
The thesis was that there's, sadly, (my interjection...I think the Taliban are horrendous) "no getting rid of the Taliban, and the Northern Alliance ain't much better (in some ways worse, according to RAWA) and that it doesn't matter who is the elected leader, he's gonna be hopelessly corrupt like the current one....and no western power ever had any success in Afghanistan and it's a morass, so...as long as Al Quaida don't have a powerful presence there, how do we (the US) get out..."