Spoilers...about Wiglaf
At the end, do you think he continued the cycle by mating with Grendel's mother?
My opinion is no, he doesn't. From the very beginning of the movie, Wiglaf is shown to be loyal, decent soldier with no desire for fame or a kingdom. I think earlier in the film Grendel's mother referred to Beowulf having the glamour needed to king. Wiglaf's character doesn't scream glamour or vanity.