Microsoft is apparently planning to take care of their Age of Mythology games series in the future. If anything, Adam Isgreen being Creative Director for Age of Empires at Microsoft saying so must surely mean it. However, this will only be done post current plans for the Age of Empires franchise, as Adam Isgreen said that they'll devote time to Age of Mythology "after we get through the Definitive Editions for the three here, and [Age of Empires] 4 is kind of rolling".

Age of Mythology takes a pretty creative look at mythology (which could be seen as a creative source material in and of itself), but that's part of what makes the game fun. It has already been treated to an Age of Mythology: Extended Edition back in 2014, so we'll have to wait on whether Microsoft is planning of releasing a Definitive Edition of the game, or a full-blown sequel altogether.