Winter is almost upon Afghanistan - so action must be sooner rather than later. I believe the US and Britain cannot wait longer than five to eight days before committing ground troops.
Ground forces would be committed for a very limited spell, most likely to secure an air base for humanitarian and helicopter operations. I don't see, other than special forces, lots of US and British paratroopers clambering round in the middle of winter.
The objectives would be very limited: special forces would be used to conduct operations against potential terrorists and to maintain surveillance.
This is very difficult terrain and I can't see prolonged operations as we saw with the Soviets during their Afghanistan war.
The Afghans are very capable and adapted to the use of small arms. My one certainty is that once the allies have destroyed their tanks and artillery, the Taleban will take to the mountains.
They are extremely accurate with bazookas and rifles and that is where the Soviets came unstuck. That's the culture of these people and their history.