BMW cannot market the F20 to enable a profit return in the US. For BMW to do so they have to sell a fully fledged base model which customers would not accept because it does not fit within their perspective of BMW's image.
It is the same with the Premium wagon. Only Mercedes offer a E-Klasse wagon with BMW,Volvo and Audi withdrawn because of the appeal of an SUV over a Premium Wagon. But the E-Klasse Wagon has come up against the same problem - Customers are taking the ML over the E.
BMW will offer the 3er Touring as the car was federalized at the development stage. They will not bring back the 5er Touring on the sole reason that the millions to federalise the car would not be recovered in sales and there is no justification just to generate a handfull of sales.