Although it is true that Christmas has been secularized, I don't think it is due to the replacement of jesus. But rather the distaste for Christianity that the country is developing as a whole. Sants is a totally different figure, not a replacement.
Just curious, khaaan, what's your religious background? I didn't grow up with either religion or the Santa myth, and always assumed Santa was intentionally used by religious parents to prepare their offspring to believe in Jesus as savior and the eventual return of Jesus. Children who get tangible presents from "Santa Claus" are primed to expect an eternal reward from Jesus--hey, waiting on an ethereal, mysterious, all-powerful figure to show up and reward them worked once, right? (No disrespect to religion intended -- I'm interfaith myself and went to church on Christmas Eve. I can laugh at some of the silly aspects of religion, but I like that many people are inspired to do good to others by their faith.)
While I think the source may be a bit unusual, the comparison is an interesting point. Regardless of your personal beliefs, it's easy to agree Christmas has become secularized and commercialized. Santa Claus as a secular Jesus certainly was not the original intention, but it certainly could be that he is becoming one to many children.
I'm envisioning Santa Claus having to hold a press conference to let people know he is not bigger than Jesus.