The story will end in FTL as it began in the Pilot. The SB ending will be some cliff-hanger, either Emma finally truly believing in Henry’s book or some moment with David/MM. It could also end with David truly remembering.
There will be new characters introduced in season 2, but like hjbau said, there’s plenty of story to tell with Snow/Charming/Emma/Henry/Regina. That won’t be concluded by the end of this season.