Having them separate would provide more potential storylines: Junior to college with separated parents, impact on Jack and/or Diane, parent meeting love interest, holiday, custody, kids changing schools. Then, there's Zoey not knowing anything about what's transpiring. A reconciliation definitely not happening this season, but might eventually. I don't think Tracee will be killed off; she may just fade away. Still, I think the Ruby/Dre talk is foreshadowing.
One thing I wonder is what happens to the grandparents. Ruby and Pops are Dre's parents, but one of the episodes has Dre moving into an ultra-modern house.