The only hesitancy I have about legs on this movie (I've gone with about 3.5) isn't quality, it's competition. Titanic basically had four clear months, while Avatar didn't face any serious competition till February, and those were romance movies. 2016, though? Star Wars has to go up against Ride Along 2, Secret Soldiers of Benghazi, and The 5th Wave - and that's just on one day. Then Kung Fu Panda comes around at the end of the month to take away the kids.
But I'm thinking this will probably be over 600M by the end of New Years' Weekend, so that's all gravy at that point.