I think what I'm confused about is who's where when. Wasn't Lalli supposed to have gone off with Emil before Reynir got back from his classes? Or are they all still based at the farm, Emil and Lalli still staying there?
I'd say the second one. The only people who were definitely seen leaving were Torbjörn and Siv, Trond and all the older siblings of Reynir's who didn't quit their job to marry their sweetheart. Sigrun, Mikkel, Emil and Lalli were seen
shopping for clothes in a place that
may be Reykjavik, but there is no indication that they jumped on a boat after that. Considering the implied travel times in the setting, it would make sense for Sigrun and Mikkel to wait out Kitty's training rather than go to Norway, then travel back to Iceland to pick her up once the training is done. And if the clothes shopping scene
wasn't an indication that the characters shown in it were about to leave Iceland, it would make sense for Emil and Lalli to still be around as well.
Otherwise, yes, it does look more and more like an "everyone decides to join Onni" scenario.