I was watching Harry Potter and the Deathly Hallows: Part 2
, and in the epilogue I spotted these twin boys. They can be seen off to the right when we see the Malfoys
I think they may be Lorcan and Lysander Scamander, sons of Rolf and Luna Scamander. Jo said they are younger than the children of Luna's friends, which these boys are. They're also blond, like Luna.
Also, despite the hints at a Luna/Neville romance in the movie, we know it doesn't last. Matthew Lewis said that it was a "summer fling" before Neville marries Hannah and Luna marries Rolf.