While there have been rumors and fan hopes, the creators and studios involved have not made any announcements about a continuation of the original series.
However, there are a few factors to consider:
* The success of the Netflix live-action adaptation: The positive reception of the live-action series might increase interest in revisiting the original story.
* The popularity of the franchise: Avatar: The Last Airbender remains incredibly popular with a dedicated fanbase.
* The potential for new stories: The Avatar world has a rich history and mythology, and there are many avenues for new stories.
Therefore, while there is no guarantee, a season 4 is not completely out of the question. It's possible that a future announcement could happen, but for now, it's best to consider it a possibility rather than a certainty.