The only state that might have gone to the Dixiecrats was Georgia.
Keep in mind that the states that supported Thurmond and Wright were states whose DEMOCRATIC electors were pledged to Thurmond and Wright, and where Truman and Barkley were running as third party candidates. They were also the states with the highest black populations and the fewest areas of Republican strength.
The FAR more likely scenario that would have thrown the election into the House would have been if California and Ohio had narrowly went to Dewey instead of Truman. California (25 EV) went to Truman by 0.44% and Ohio went for Truman 0.24%. This would have resulted in a 242 (D) to 239 (R) to 50 (Dixiecrat) in the EC.
The Democratic Party was such at that time that the Southerners would have been motivated to make a deal to re-elect Truman. They were not in a strong position after the 1948 elections, and Dewey was not a Republican candidate that was appealing to Southerners. It's certainly possible that the Dixiecrats would have bolted to Dewey, but they wouldn't have enjoyed it and Dewey wasn't the kind of Republican that would lead Southern Democrats to leave the Democratic fold.
It should be noted that Dewey didn't campaign in the South. Four years later Dwight Eisenhower actively campaigned in the South and won VA, TN, FL, and TX. I do think that if Dewey had campaigned in VA, TN, and possibly TX, he may have carried those states, but he didn't do that.
