Looks like Unity of Command 2 Axis missions are coming By Jonathan Bolding news The newest Beta patch for the wargame has a Battle of the Bulge test mission.
Unity of Command 2 will be out in November, beta signups are open By Andy Chalk news The closed beta is expected to start in a couple of weeks, and will require some serious commitment from testers.
Unity of Command creator starts a development diary for the sequel By Andy Chalk The Unity of Command sequel hasn't actually been announced, but it's coming.