[Jmacq1]

There's not going to be any sort of "grass roots" success for John Carter, no matter how much good word of mouth it receives. "Titanic" came out in an entirely different time and place for movies (before DVD was commonplace, when movies would play in theaters for months at a stretch if they did well enough...now no matter how successful a movie is, it's out of the theater in two months, tops because the DVD/Blu-Ray probably comes out a month or two after that).

It is unbelievably rare now for a movie to actually increase in grosses after its' opening weekend. John Carter may as well already be getting shuffled off to DVD/Blu-Ray, because it's basically going to lose all of its' screens after this coming weekend (to The Hunger Games and Wrath of the Titans). John Carter's best hope is for it to do really well overseas/outside the US, but even then the reports are saying the movie would have to make about $400 million total (between domestic, international, and home video) to really be considered a success.

And yes, when your movie costs $250 million to make, a $30 million dollar opening weekend is bad news. That's the same reason that Tron: Legacy and Green Lantern were considered "disappointments" despite making over $172 million and $116 million dollars, respectively.