As the finale got going, I think most of us expected a Tarantino-esque bloodbath. Instead we got Kill Bill Vol. 2, with Ava as The Bride. Well played, writers. Well played.
Was the "four years later" - not three, not five - a sly tip of the (white) hat? I'd like to think so.
Incidentally, I always felt a QT vibe from Justified, what with all its lavish respect for its characters and dialogue. Don't forget that his Jackie Brown was an adaptation of Mr. Leonard's "Rum Punch", so he's something of a kindred to the show.