Unless this is setting up Adam beating Clark and Clark has to call Billy for help.
That wouldn't be an especially auspicious or inspiring return for Cavill's Superman. OTOH, the Rock seems to be steering this particular ship, and I doubt he wants to have Black Adam's ass handed to him either. Probably the most likely thing is the classic comics scenario where they initially duke it out, only to find themselves teaming up against a greater threat.
Amen to that.hopefully Amy Adams will return as well.