(Correct me if I'm wrong but...) By US law the local bishop owns all diocesan property. If there is open schism, with US bishops separating themselves from Rome, Rome will have no recourse to keep the institutional structure, and the US gov't will support the rights of the local hierarchy to control Church property. Unless an individual bishop sides with Rome, most Catholics would be churchless if they want to stay Roman Catholic.
Thus the Pope has not used an iron fist with the US hierarchy, as they have threatened open schism if he does. A bishop lasts a lifetime. Schisms last centuries. But the loss of an eternal soul of a victimized child lasts for eternity.