What Does That Mean for Christmas?

As long as we're confined to the solar system, i don't think we would create a new calendar. The solar system is only like six light hours away from pluto. But if we start colonizing alphacentauri or beetle juice then even further away a precedent will already have been set of planets other than earth's celebrating christmas in with earth. And since jesus was born on earth, there's going to be a strong tendency to want to celebrate his birth in conjunction with its celebration on earth.