It is very likely that there will be an official announcement regarding the VIE-ORD flights soon. Nothing official yet, but the new joint-venture service with UA is rumored to start on May 2, 2013 and will likely be operated by a 767. By this date, all planes in the OS longhaul fleet will already be equipped with new seats in C and Y as well as an AVOD-entertainment system in both classes.

Source (german only): austrianaviation.net