Someone on TV Tropes brought up a very good theory regarding possible foreshadowing in "Food Chain". It concerns Erin, the female caterpillar Finn was marrying. The TV Tropes user theorized that Erin is foreshadowing for a future love interest for Finn. So she's not just a one-trick pony. She's a new plot thread.

My evidence? As they were falling to their deaths, Finn vowed to marry Erin in another lifetime. This "another lifetime" is likely Finn's current life.

And since at the time, Finn was a caterpillar like Erin, this means that Erin will likely be a human. Which is a prospect I like. Erin seems like a really nice person of a different cloth from PB (who's slowly becoming evil) and FP (who refuses to forgive Finn and is possibly dating CB).