This comes across as (perhaps unintentionally?) overly cynical to me.
I purchased Factorio some years ago now, and have always had the feeling that I underpaid for it over that time despite playing a lot less than some friends I know. (I think I have a mere couple of hundred hours playtime which for any other game would be crazy high!)
The devs have continuously worked on it in all that time. It’s not as if they had a bunch of expensive DLC lined up from day one as some AAA titles seem to these days.
I paid $30 for 90 hours of entertainment. That's how long it took to finish one game with my friends. You'll have a hard time convincing anyone that $0.33/hour isn't amazing value for entertainment.
Whatever they price their expansion at, it'll be worth the money.
After I got all the achievements I started playing some mod packs. About a year ago I found a nice discord group that does a new map roughly every month. It’s full of mods and different things. Yes it’s still factorio but we have a pretty small group of dedicated players who enjoy hanging out online with each other and factorio is how we choose to do it.
The overhaul mod packs can pretty drastically change the game experience. It scratches the programming itch while being a break from actual programming.
I’m sure the pandemic added a multiplier to those hours that I wouldn’t have seen otherwise. But I’m quite enjoying it.
The game only really begins once you launch your first rocket. There is so much gameplay hidden in trying to improve the productivity of the initial factory. Playing with tough aliens makes it even more challenging/satisfying.
It's basically them saying we consider that the next version we will ship corresponds to the work we promised (which is more than true).
Now, they want to extend this base game and are announcing that they will come back in a while with an extension. There is no subscription shenanigan, no weird trickery with you surrendering your data. They sold us something and delivered and will now work to offer another thing at a price of their choosing. Something that people will be able to buy it if they do desire and knowing what they are buying.
That seems refreshingly straightforward and honest to me.
The game is remarkably affordable in terms of hours of enjoyment vs price. I feel like they could make an 'expansion pack' that cost twice as much as the game and it still would be a reasonable value.