I'm guessing we might be approaching the end of the Planet Coaster 1 lifecycle.
According to this, we might have two updates this year, the one they're currently working on, and the one that would bring the Thememaker.
The Thememaker is to me also the end of paid DLCs. It makes sense to open up the game for custom scenery once you've decided not to continue creating content for it. And otherwise, outsource it to the community, so the game's lifetime is extended by it for some more years.
The interesting and good news about it is that once Frontier is no longer working on DLCs, and the community is supporting the game for some more years.. the developers can focus on Planet Coaster 2. That should bring new dynamics and features not possible with the current engine or core software with more DLCs based on version 1 of the game.
[repost from reddit]
EDIT: Since this may cause confusion.... Approaching the end of Planco 1 lifecylce in favor of a new Planco 2 lifecycle or whatever WOULD BE GREAT NEWS. With UGC Planco will be better than ever, and will extend its lifespan, relevance and user base for sure. I'm also not saying Frontier won't be supporting the game or expanding it.