Presenting a scenario 60 years after Canada, Iraqi Kurdistan, Kenya, Hainan Island and Taiwan are ISOTed to a virgin earth:
Currently the most developed and stable of the surviving nations is the Republic of Canada, which has benefitted tremendously from access to the resources of its former neighbor to the south. It is considered the eminent power in this new world, with room for expansion with new colony territories in the American South and Russian Far East. The country has maintained Westminster-style parliamentary government with an elected figurehead president in place of a monarch. Canada's chief concern is developing its agriculture and maintaining cool, if strained, relations with the State of Quebec, especially in light of the latter's expulsion of Newfoundlanders/Labradorians during the brief Quebecois Secession War. Interestingly, these same refugees would be involved in the settlement of Canada's new southern provinces, an ironic echo of the 18th century Acadian expulsion.
The second eminent power of this world is Kenya, which boasts the largest population of any extant nation (nearly 100 million). Though the country suffered chaos and near-collapse in the short term after the Event, a group of technocrats seized the opportunity and ultimately managed to marshal the country into sufficient shape to withstand the challenge of surviving in the new world. This TL's Kenya is a quasi-authoritarian welfare state dedicated to self-preservation and self sufficiency with modest xenophobic tendencies. The country now dominates the Horn of Africa, the Red Sea, and even splits control of Cyprus with Great Kurdistan.
Great Kurdistan is the poorest of the surviving powers. Originally the Iraqi Kurds felt like they were in paradise, having seen all opponents to their long-held ambitions vanish overnight. However, the reality of trying to construct and maintain a modernized state without a global economy and only modest domestic development soon proved an obstacle. Great Kurdistan certainly holds considerable control over the Middle East (with the exception of Cyprus) and is peaceful. However, it is by far the poorest nation, and in many areas appears to resemble the 19th century in terms of technological and economic development. Kurdistan 50 years on is a democratic petrostate, the number 2 source of oil (number 1 for Kenya) after Canada. The nature of Kenya's dependence on Kurdistan for oil and rivaling territorial expansion has resulted in tensions between the two.
These tensions are dwarfed in comparison, though, to the cold war simmering between the Taiwanese Republic of China and the Hainanese Chinese People's State. The question of Chinese governing legitimacy has continued even after the Event. Democratic Taiwan had a leg up in the short term post-Event, was able to quickly recover from the shock and proceeded to colonize the mainland in the name of realizing a greater China. Hainan, on the other hand, experienced significant upheaval with the sudden end of contact with the command structure from Beijing. Ultimately a civil war ensued resulting in a hardline revolutionary faction taking over and reforming Hainan as the Chinese People's State. Eventually the two Chinas came into conflict, waging a war that stalemated and ended in the creation of a buffer state (the Pacific Republic) based out of Hong Kong Island between them and peopled by foreigners/tourists who were trapped during the Event. Though the war ended 25 years ago, the two Chinas still maintain an aggressive arms and colonization race. Taiwan economically and demographically is superior given its resource-laden Yellow Sea colonies, but Hainan's military buildup is becoming harder to counter.
In general the nations of TTL only interact with those closest in their regions. Canada is the sole power that maintains strong international trade with all nations, creating a strong merchant marine in the vein of the US and UK before it. The Republic of China conducts trade with nearly all powers save the CPS. The CPS and Kenya are isolationist, though the latter to a lesser extent (Kenya charges Canada and the ROC to access its New Suez Canal). Quebec remains aloof. Greater Kurdistan largely carries on and develops, while the Pacific Republic worriedly sits in the middle of a potential warzone. There are no standing international alliances at present, although the CPS has been sending feelers to Kenya about a possible future defense pact. . .