Well that end of the last Lord of the Jungle was a clue. Dynamite has announced that Arvid Nelson and Roberto Castro will be doing a six issue miniseries where John Carter and Tarzan meets. Comic Vine posted up this description and some comments from Nelson:
In LORDS OF MARS #1, the legendary Tarzan has claimed his title as Lord of Greystoke, but his very life is threatened when a hunting excursion with his fellow "gentlemen" goes disastrously wrong. Meanwhile, on Mars, John Carter is forced to respond to a veiled threat from his defeated enemies. Mars and Earth might be separated by millions of miles, but a sinister force is at work on both planets, setting the two iconic adventurers on a deadly collision course.
"The two greatest heroes of pulp fiction coming together... what could be better than that?" says Arvil Nelson, writer of the six-part miniseries. "And it blows the lid off the possibilities for storytelling. Earth, Mars, lost civilizations, hidden worlds, interplanetary adventures. But above all, we want LORDS OF MARS to be fun. I can't wait to unleash it on the world."
The series is set to begin this August. To see more cover art and some pages from the first issue hit http://www.comicvine.com/articles/exclusive-john-carter-tarzan-team-up-in-lords-of-m/1100-146568/