What will most-likely that will happen is that Treyarch will bring back the Tranzit crew ( Russman, Misty, ect.) in another installment of zombies.
Like you have said, Treyarch has wrapped up the Richtofen Crew with ,in my opinion, a very vague cutscene.
Treyarch will bring back the Tranzit Crew for these two reasons that i think why.
1. The Tranzit Crew just disappeared and got replaced by Richtofen's
2. We still don't know why the Tranzit Crew is in the Zombie universe and their purpose.
So those are my speculations of what will happen in the maybe very near future.