Michael Chabon is one of the script writers on Disney's John Carter of Mars movie. In an interview with ERBzine he gives us our clearest indication yet exactly what Andrew Stanton is going to do with Edgar Rice Burroughs original Mars novels. How the script is going to translate the books into a form suitable for film.
As someone who works in entertainment (video games) I understand why intellectual properties are changed to fit the needs, the strengths and weaknesses, of a different media. As long as it is done with respect to the original property, and isn't changed for the sake of appeasing the director's own ego or some ridiculous marketing demands, it can work. Staying true to the spirit of the original is how you can embrace the fans of the original and bring in a whole new audience.
Spiderman 2 is a good example of this, and to a lesser degree X-Men 1 & 2 did it also. Take the original seriously and with respect, not as some big fat cheesy joke (like Batman & Robin, Starship Troopers, Godzilla...)
Here is the interview: