But due, in part, to a categorically slow time of year for football news, many have taken to prognosticating in the question's general direction. The one theory that seems to be the most popular--and, for that matter, the most reasonable at the moment--is the Chicago Bears.
The thinking behind it goes something like this:
Since the game will air on Fox, Dallas's opponent will be an NFC team, leaving Washington, New York, Philadelphia, Detroit, Chicago and New Orleans as possibilities. The Cowboys haven't played a division game on Thanksgiving since 2002; the Lions are out, as perennial Thanksgiving hosts as well, which leaves New Orleans and Chicago.
The factor that makes an NFC East Thanksgiving Day match-up a long-shot--a general feeling on behalf of the league that people will watch as a matter of tradition, almost regardless of the game--also makes it unlikely that Dallas would face New Orleans, a game that will draw a huge rating no matter when it's played.
Dallas last faced the Bears in 2007; in 2004, the teams met on Thanksgiving Day, a 21-7 Cowboys win.