The lack of interest in the Titanic re-release confirms a view I have held for a while, that Titanic was a fad that was the right movie at the right time in 1997 and hasn't held long-term interest like other classic films such as The Wizard of Oz, Jaws, The Godfather, Star Wars, Indiana Jones, E.T., etc. I mean I don't know a single person who re-visited it on DVD.
The fact basically every single 3D re-release so far including the dreadful Star Wars Episode I is out-performing it pretty much is falling in line with this.
I don't think you can draw these conclusions at all. E.T. was re-released 10 years ago in 3000 theatres and only managed $15M in its first weekend, and $35M total. Toy Story 1 + 2 were re-released in 3D as a double release in 1700 theatres and only grossed $12M in their first weekend. Were those movies fads too?
Star Wars Ep1 3D only made 22M in its first weekend, and 43M total. Titanic is already at 15-16M after 3 days and due to the holiday weekend, it should be close to 30M by Monday. I think it has a pretty good chance at passing Episode 1 by the end of next weekend. It won't touch the Lion King though.