World-System (WS), which according to Norbert Wiener's works on cybernetics can be defined in terms of an input, a process and an output, has lost its feedback because of gradual narrowing and consequent shut down of all bottom-up communication channels (a direct result of power's over-concentration). That might lead to WS collapse in the nearest 20-30 years.
That will happen in three stages:
first: over-centralized governance centers (on countries' and states' levels), which are responsible for adjusting societal processes to changing exogenous parameters, begin to send wrong signals to outputs. It leads to further deterioration of inputs. As a result this cycle soon become self perpetuating (like in an overheated boiler with damaged relief valve). That will initiate a compensatory reaction in all governance centers, which includes objective information denial, an aggressive suppression of individual non-compliance and social resistance, introduction of more rigid regulations and power monopolization by military complex. This will increase tension of inter-governmental relations on the world stage.
second: a gradual accumulation of entropy in world-system will lead to series of technogenic crisis (specially in highly militarized regions of the planet). One of those crisis will soon grow into a small / medium scale kinetic confrontation where tactical termonuclear devices will be deployed. Resulting hysteria, augmented by mass medias, will lead to a sharp radicalization and further centralization of governments in the hands of special forces, police and generals in many countries. In one of those countries, where processes of increasing social, economic and political entropy is slower than in others, a narrow group of militarized elites will soon decide to take advantage of quickly deteriorating situation in other countries in order to establish their own global dominance and prevent the world from further sliding to chaos.
third: this country (countries) will start an economic, cyber and, soon, military assaults to the most weakened states. Other countries will threat this conflict(s) as a postponed threat to their own national security and back the attacked sides with their own military support. This process will quickly avalanche and get out of control. 50 - 100 megaton nuclear devices will be deployed to several highly populated regions across the globe. Global hysteria, mass exoduses, radioactive fallout will collapse most of the world's states including all of G20. However, some of smaller ones, unaffected by direct bombardments, will hold. World will be divided to several regions (safe Internet and long-range flights) disconnected by large contaminated zones.
fourth: To survive smaller sates will have to reach a temporary peace agreements. Terrorized and horrified by global war atrocities population will vote (or forcefully take out) militants out of power in most post-war democratic countries. In former authoritarian states smaller number of dictatorships / kingdoms will proliferate. World will be further divided to micro-states with very different forms of governance.
fifth: because Internet will survive global war trade and tourists connections will soon be re-established and new kinds of decentralized governments will start to slowly replace local small dictators and representative democracies. Because of their small size non of them will be able to resists the growing decentralized world governance model.
Let us hope that we, collectively, we’ll be enough sloppy, non-organized, uneducated and mathematically ignorant to not allow this scientific scenario to materialize.