It's a bitterwseet sequence, and seems to foreshadow the breakup of Hillary and Jon. Or is it? When we start reading, we think we're reading third-person omniscient narration -- but it's Nona talking. When we flash forward to next summer, it's not clear if we're seeing reality, or just Hillary's imagination.
Sometimes adventure strips, such as Judge Parker or the Phantom, will have some foreshadowing. A single panel will introduce something that won't be explained for a few weeks. Usually, though, it's laying the foundation for the next story arc, so there's a smooth transition.
In this case, we had to wait three months -- and several other story arcs -- to see if what happened next.
To my knowledge, no comic strip has been this far-ranging in setting up a story arc. Brilliant.