It will be hard to tell given how the holidays fall. I think it will be a heavy travel day, but I think nowhere near as heavy as a normal rush hour plus weekend. We used to leave the weekend before christmas for 2 weeks in FL, but without any school age kids in the group of families traveling south right now, we opt to go after new years when its generally less crowded.
Of course, we start in Northern VA and skip DC entirely by using 234, but we take 95 from there south and rarely encountered much in the way of stop and go traffic.