I doubt the Taliban will be able to grab power again the way they did in the 90's. They will be a major force for sometime, but what is their focus? I suspect their ties with the ISI are now tenuous at best and they have the habit of biting any hand that feeds them. Pakistan is losing it's main hold on the US and I suspect that the US will start reducing the money given to Pakistan, forcing them to be a vassal of China and China has no real interests in a radical Taliban controlled state near it's borders, in fact a neutral or semi-friendly Afghanistan is likely far more useful to them.