I suspect it will be very crowded, but not as crowded as the week between Christmas and New Years.
Weekends around the holidays can get pretty crowded, and once schools are out, the parks start getting very crowded, and the crowds seem to grow the closer you get to Christmas This year could be funny. My son's school doesn't get out until the 22nd, but my work is shutting down on the 15th. I suspect most schools get out on the 15th as well. One clue to the crowds is the schedule. I believe the park is scheduled to be open until midnight on those days. That usually translates into big crowds. Still, I love to go at this time. The holidays are so magical.