The problem with Carson of Venus (from Dynamite's point of view) is that it ISN'T in the public domain. Which means they would have to officially license the title from ERB Inc. Consider that ERB Inc. has pursued litigation against DE for their publishing of Lord of the Jungle and Warlord of Mars (both of which ARE in the public domain) -- they aren't likely to want to work with DE.
Any current Carson of Venus adaptations would need to come from Dark Horse Comics, who are still the official licensees (as far as comic books and graphic novels are concerned) of ERB-owned titles. Regardless of the fact that they've released exactly ONE new comic book (The Once and Future TARZAN) in the last decade and a half, along with their many reprints of ERB comics.
DE pull list: The Shadow: The Death of Margo Lane, The Lone Ranger and The Green Hornet, Six Million Dollar Man: Fall of Man