I don’t recall them ever announcing what the next port would be after the Khanate. There’s enough in-game content adjacent to Irem to indicate that it’s on the radar, but nothing about when it might be or what else might be next.
I would be a little surprised if new content dropped before Fruits of the Zee. And if new content does drop, I would expect TLUpolis before another port, but that’s just a guess. Still, that gives a good two months between Fruits and Hallowmas.