In the VERY FIRST game to finish, 11 seed Dayton upsets 6 seed Ohio State. Nate Silver had given Dayton a 25% chance of winning, so just about everyone who used his numbers as a guide is out now. Buffett's odds just got MUCH better.
I think in a conversational sense, they didn't really change, just because the reasonable conversational description of the odds was ~0 to begin with.
Not that anyone is going to win his money, but this one game doesn't change anything.