Merriam-Webster wrote:
Foreshadow: to represent, indicate, or typify beforehand : PREFIGURE
This strongly implies the intent of the author, so I am inclined to agree with you, Eldorion. The Battle of Five Armies was the culminating battle of Hobbit, and served as the climax of the story. And it was written in a way that is a lot more innocent than LOTR. The elves, men, and dwarves were bickering amongst themselves and were pretty much at a stalemate when the orcs came and everyone had to unite against them. In the end, it becomes a curtain call. Beorn shows up, along with the Eagles, more dwarves, and Gandalf. It's somewhat absurd, in it's own little way. And that is what makes it the Hobbit. In LOTR, there is nothing absurd about the battles. They are all very important battles, and are battles that were written in the history books for thousands of years afterwards. They had high stakes, and they weren't there to show off all kinds of fairy tale creatures.