Why would USA do that?
US does not need to attack Pakistan to strangle it to death. That is possible within a few months. For the groundwork, US will be only too happy to let Indian Army do the hard work. Israel is the wild card in this picture.
One more thing, Pakistan is running out - or already has - of chances to bare its nuclear fangs.
The idea is not occupy Pakistan territory. With occupation of territory comes the responsibility of feeding 140 million people!
Think Serbia (1999) - Iraq (1991) model of warware!
Just keep bombing from high altitude and destroying the military and Industrial ifrastructure, till the other party capitulates! USA is good at it, Pakistan will have no chance.
I am going to stick with my earlier assesment, Pakistan will do the same what it did in post 911 scenario, capitulate!
The option would capitulate imeadiately or capitulate after two months of bombing, which one do you think is better?