All great societies must fall as it is an inevitability. It has happened many times in the past with the dark ages that have spread across Europe with the fall of the Roman empire proceeding the medieval period and when the Greek empire collapsed which started the Iron Age. Human nature hasn't changed much since then, but we have the tools i.e. WMDs to make temporary lulls in progress more long-lasting (or permanent). The same mistakes are being made every day that will lead to the inescapable end of the majority of what we consider modern living.
It may come tomorrow or it may not happen for another thousand years, but the warning signs are blatently obvious. Increased militarism, imperialism, nationalism are moving that doomsday clock forward along with a societal lack of education, the proliferation of cheap weaponry, and ideological reasoning being put ahead of logical reasoning. Its the human condition shared by all the world leaders and the terrorists who antagonize them. The only solutions being offered are band-aids for a gaping artery wound because it would take almost a complete overhaul of thinking to take the steps necessary to reverse the path we are leading outselves down.
Einstein also said that "You cannot simultaneously prevent and prepare for war" as well as "I know not with what weapons World War III will be fought, but World War IV will be fought with sticks and stones." Although the technology he helped develope may one day destroy us all, he very much believed in the futility of war and the general idea of different peoples, cultures, and socieities putting their resources towards a common good instead of destroying each other. We are a long way off from that unless some outside interference comes that scares us more than each other.