Final answer:
The best prediction for what might have happened if Maya cities had ceased their warring is that the Maya civilization might not have faced such a rapid collapse, potentially leading to a stabler society.
Step-by-step explanation:
The best prediction of what might have happened if Maya cities had stopped warring with one another is that the Maya civilization might not have collapsed in the same manner. Warfare amongst the Mayan city-states was a significant factor in the society's eventual collapse. If the cities had ceased their conflicts, other factors, such as environmental degradation, resource depletion, and demographic pressures, may have been mitigated or eased, allowing the civilization to adapt and possibly avoid the rapid decline that occurred. The cessation of warfare could have led to a longer-lasting, more stable Mayan civilization, potentially sparing the monumental architecture and urban centers from being abandoned as they were following the classic period around 900 CE.