Guilds was the final expansion. This new one is the first Extra Super Bonus expansion.
Alchemy was the final expansion. It was the large expansion I could quickly split in half, so it got bumped up when they wanted a small set.
So then Dark Ages was the final expansion. Guilds, post-dating the original expansions, I made just to come out in between Hinterlands and Dark Ages, to keep alternating small/large. Then Jay put out the Base Cards product and pushed other stuff back and it seemed like, if you only get one expansion in a year, it should be the large one. So I argued for switching the order and he did.
So Guilds was the final expansion. Then I made another one. I wasn't getting a spin-off made and I needed an easy project.
I feel like I explained clearly, over and over, that there might be expansions after Guilds. For sure if it wasn't clear before, this expansion coming out clarifies it.
I don't know how many more expansions there will be after Adventures. It depends heavily on whether or not I manage to make spin-offs, and how well they do, and what other things I think of to do for Dominion. In retrospect Adventures could have been a spin-off - not the kind of spin-off I have been intending to make (i.e. I have been intending something less similar to Dominion), but the kind I originally planned to make (before an endless parade of other people made those).