Sorta what we’ve been predicting–the arc of this season ends in 320 (Facilier and Gothel both leave) and it’s really a character story to carry us through the rest of the year. There’s no real big bag except for whatever Henry is wrestling with.
Based on what we’ve heard from filming, I bet this “new threat” they’re teasing is Wish Henry. He could still be out for revenge for Regina killing Wish Snow and Charming.