The devs implied at least two more updates. (at the time they were at 0.9.4 and said they could be done in 3 updates)
So if they stick to their current plan they might finish by 0.9.7. If they add more stuff then there could be more updates. They expect to finish before the end of the year. So at the rate of 1 per month that's anywhere from 0.9.7 to 0.9.9.
Personally, I really hope they take their time and add more scenes. I'd be fine with them not rushing, taking extra time to make the updates bigger and ending with patch 0.9.9 somewhere between Jan 2022 to March 2022. And then taking months off before starting on the epilogue/book 5.
https://f95zone.to/threads/four-elements-trainer-v0-9-5b-mity.730/page-1198#post-6366177