This should be fun. Flying back from Canada YYC > DFW > AUS the week after Christmas. Original flight schedule gave us ~3.5 hours to connect and clear customs with checked bags. AA changed the schedule, and now we have exactly 1 hour for the same connection. We have a lot working in our favor - Global Entry + PreCheck + Clear (not sure if the latter helps in this case), but 1 hour seems awfully tight. I guess the wildcard will be baggage claim after customs. Coming back through MIA a couple weeks ago, it took over 30 minutes to get our bags at customs, then a HUGE line for security afterwards - no PreCheck option.