There have been movie ideas bouncing around on this for decades, but maybe this time it will really happen. The ERB corporation has kept applying for trademarks on John Carter for so many decades without actually producing any commercial product that I question whether or not its trademark is even valid anymore.
Of course, who else would even try to use the John Carter story these days. It's going to be hard to make into a movie for mainstream audiences unless the characters wear a lot more clothing than they wore in the books, or even on the covers of the books! It's also going to be tough to sell the idea of people with advanced technology and projectile weapons who prefer to fight with swords. ...then again, maybe not, considering the success of Star Wars.
The first three books didn't have the greatest story lines. I liked the ideas in some of the later books better, including "Thuvia, Maid of Mars," "Chessmen of Mars," and "Mastermind of Mars."