When the "others" left the alcatraz sized island did the kids come with them? There was two boats I think, one that was already off shore then the smaller boat ben, juliet, and jack were on. The kids could have been transported on the other boat already off shore I suppose. We know Alex came with them to the barracks, she is considered one of the children, I think. We don't know much of anything about the barracks, there could be underground areas, or the kids could be discussing a harry potter book in their own book club next door to where Kate and Jack were talking. It's pure speculation with a phrase like "they are safe"