The short version is UNC will likely end up the #10 seed at the ACC Tournament in Greensboro and play next Thursday at 7:00 PM on ESPN2 vs Georgia Tech.
According to Patrick Stevens of the D1sCOURSE blog, UNC's seeding is fairly basic. If the Heels lose to Duke or Virginia wins then UNC will be the #10 seed. If UNC beats Duke and Virginia loses the UNC can move up to #9.
As for possible opponents, Boston College is locked into the #8 seed so if UNC moves up to #9 they would get the Eagles at noon next Thursday. If UNC is the #10 seed then in all likelihood it will be Georgia Tech at #7 though Wake Forest could still flip slots with the Yellow Jackets. Here are the scenarios as laid out by Stevens(relevant lines in bold):
No. 5 with a win AND a Florida State win
No. 5 with a win AND a Virginia Tech win AND a Florida State loss
No. 6 with a loss AND a Virginia Tech win
No. 6 with a win AND a Virginia Tech loss AND a Florida State loss
No. 6 with a loss AND a Georgia Tech win AND a Duke loss AND a Maryland win
No. 7 with a loss AND a Georgia Tech win AND a Duke win OR a Maryland loss
No. 6 with a win AND a Wake Forest loss AND a Duke win OR a Maryland loss
No. 7 with a win AND a Wake Forest loss AND a Duke loss AND a Maryland win
No. 7 with a loss OR a Wake Forest win
So who would rather see them play? A rematch with Wake Forest two weeks after beating them in Winston-Salem in front of what stands to be an even crowd? Or would you rather see the Heels take a 3rd shot at Georgia Tech with what is bound to be a pro-Carolina crowd? Wake is in a full blown swoon. Georgia Tech beating UNC threes times would be tough. On the flip side, both teams offer a variety of matchup issues for UNC, especially Georgia Tech.
In other words pick your poison. The best scenario is winning at Duke and hoping for a UVa loss to get the #9 seed. That means playing Boston College who will have a grand total of fourteen fans in Greensboro.