I think you've stated before that most of Dominion's playtesting was done with 3 players. Dominion is also incredibly popular with 2 players. The player range for Temporum is listed on BGG as 2-5. At what player count did you do the most testing? Which player count(s) do you prefer, and what do you anticipate being most popular?
Are expansions for Temporum already in the works? How many are planned?
I'm not sure I have actually played Dominion the most with 3; probably the quote was just, that I cared most about balancing it for 3, because that's how you try to get things good for 2-4 (I never worried as much about 5 although I worried some; I would not have supported 6). In the early days I played more with 2 or 4 than 3, though I also played with 3.
I actually recommend Temporum for 2-5. Publishers often stretch the range, but that didn't happen here. The game does vary between 2-5, in particular via ruling times. With 2 you have the classic situation where hurting your opponent lines up so well with helping yourself; in particular you'll struggle to stop them from ruling times, even when it just means tying so no-one rules it. With 3 you will care more about ruling a time yourself, since stopping someone else (without ruling it yourself) is just hurting one out of two opponents. With 4-5, two players can rule a time. This means that if I'm getting a huge advantage somewhere by ruling and also I'm not tied for most, then you can't personally just stop me by yourself - you get more crowns than me there and well I still rule there. Overall it's easier to rule places (although of course changing history can temporarily get rid of the place that's good for them). It's easiest with 4 since at 5 there is more competition. And then besides ruling, some abilities hurt all other players, so you get hurt a little more that way with more players. And obv. the more opponents you have, the more likely that one of them will get lucky in some way.
I have played less 2-player Temporum than any other player count; I have certainly played a lot with 5, because that's where any additional people have to get turned away. I've played with 2 though and it works well. I personally prefer the more social experience of more players. It's slower with more players because you take turns, and nothing at all compensates for that, it's just slower; but it moves at a fast pace even with 5 so it doesn't really matter.
I don't know how to guess what will be popular. I guess since sometimes you have 5 and are limited to games that work well with 5 and this does, 5 will see some action. There are so many choices for 2. Online play has pushed 2-player for Dominion; dunno if Temporum will get an online version. Also Dominion can be played by couples in a somewhat non-confrontational way; Temporum is more confrontational. OTOH lots of people play 2-player confrontational games.
I made an expansion for Temporum, but whether or not it comes out will depend on how well the game does and stuff. I haven't planned on a second one; there would need to be demand and I would need to think of more stuff worth doing.