An end to the NuTimeline.
Just as St: Eleven began with a "split,
ST: Thirteen will end with a "merge
Maybe something similar to the end of the episode The Year of Hell where something big and flashy happens (it is a JJ Abrams movie) and the next thing we see it a TOS style Enterprise sailing through the suddenly peaceful universe with a voice over by Kirk indicating they're on a routine mission and all is well.
Dear God, I hope not.
I want as few "nods" to other Trek as possible. If there must be some, keep it simple like "the Mudd incident" (though even that seemed a bit forced) or drop a few familiar place names into a conversation. No need for anything obvious.