Major updates right about 4x/year, sometimes longer/sooner depending on the dev's personal life but pretty damn consistent overall for several years now. Patches and minor updates tend to be about a month after the major updates.What has been the update rate of this game? It's still posting updates, but I'd probably just check back in a year or so to get a bunch of new content
The game engine is reaching its limits and the dev is focused on completing the Main storyline, the remaining "open" Side storyline, and filling in certain areas. Which could take anywhere from 4-8 major updates (1-2 years). If the engine can handle it once those are done they might add more content that they/the playerbase were interested in before the approaching engine limits became obvious.
Some players also hope that even once the game is "done" the dev will invest some time to update images/vids/maps created early in the development process to current standards, for consistency, before moving on to their next project. And pretty sure I'm not the only one who'd be very interested in a full rebuild using the knowledge & skills they've gained.