I've found things like this to happen on pretty much all airlines, especially since I frequently travel on holidays. CO just canceled an onward connecting flight I had home out of IAH on 12/31 in the evening, and couldn't get me home from AMS at all that day due to new year's eve cancellations out of both IAH & EWR [when I booked the ticket, either were valid connections]. Then, they canceled AMS-IAH completely on 1/1 too. So I had to do a lot of shuffling but it all worked out. Nothing surprising about NW doing the same really.