Third part of Kaiji wasn't that great since it was only one game and the fourth part is not that interesting either, in my opinion, which is a shame because it kind of wastes Kazuya as a villain (and I think he has the potential to be a great one, like his father). Either way, if they did a third season, I would still watch it because Kaiji is Kaiji.
And I know Akagi is still publishing, but the anime's ending was a HUGE disappointment. They built up the tension (because Akagi wasting his blood away with cigarette ashes was 10/10) and then they just left it there. At this point, even an OVA would be a miracle for both of the series because if I recall they didn't sell very well (which is ironic since both of the manga are really popular in Japan).