Let's start with some good news: We have no reason to believe that BMW won't offer its capacious 3 Series here in the United States. The Touring has been a part of the 3's lineup in the U.S. for decades, and BMW executives have already confirmed that the wagon will be offered here in the States.
Like the outgoing 3 Series, expect just a 328i model in rear- and (forthcoming) xDrive all-wheel-drive formats. Of course, other markets will get some tasty diesel options, but since the wagon doesn't account for a huge percentage of 3 Series sales in the U.S., having one engine option will likely have to suffice.
Look for the 3 Series Touring to launch in the near future ( Geneva Motor Show?) with the first cars hitting the ground in Europe this fall.