An interesting take, from an e-mailer:

I’d like to respond to the “Ban Christmas” concern, if I might. To the glee and comfort I’m sure of all, the federal holiday of Christmas will not be banned.
One simple reason: Baseball.
“Federal League v. National League” (the SCOTUS ruling that said that “baseball is not a business”) is laughable on its face. (Though conservatives and liberals would likely disagree why. Conservatives would agree with Oliver Wendell Holmes that all of anti-trust law is “damned nonsense” and give it all the boot. Liberals would say that anti-trust law belongs everywhere.)
But no thinking person can believe Federal League is sound. This “tradition” actually is a silly anomaly that should go. Moreover, some monetary ramifications, probably throughout the economy, would occur should Federal League be reversed or legislated away. And out of tradition and honor for the past, “stare decisis” rulings have been issued to the decision time and again.
Now, the notion of “Christmas” as a federal holiday may strictly also be an anomaly. But it is much more deeply entrenched. It’s religious, and older than baseball. Realization of Christmas leads to joy and giving; realization of Federal League leads (in theory) to oppression and lack of rights among players. Many more businesses count on Xmas being a holiday than count on baseball being not a business (but both camps are substantial). Many more people would be [ticked] off over that than would CARE, either way, about the fate of Federal League.
It’s a fair question, that. But I believe a lot more than an interpretation of the Equal Protection Act and Establishment Clause would have to change for the “privatization” of Christmas.