The OP’s offering is pretty plausible, although I’d dispute the independent Tibet and Quebec and the separate government of Taiwan. More generally I don’t see huge boundary changes among developed nations. As the economy becomes more service oriented, territory becomes less important and nations will compete over it less. (China won’t take over Siberia, it’ll just buy up its resources.) In general governments will become more centralized and powerful until they are too large to function well - it’s an even bet whether the US or EU will reach the breaking point first.
A more interesting question is who are the major players going to be? My predictions (and bear in mind this is essentially the same as asking “who from high school is still going to be cool 20 years from now”):
United States: contrary to partisans on both sides, there will be no dramatic slide to socialism or theocracy. Government will continue on its slow expansion trajectory, and the economy will resemble the EU of today, fairly wealthy (much wealthier than today, of course), but undynamic, with high tax rates and more regulation. It will however still be the cultural center of the world and a major diplomatic player.
China will have had its run and become the largest economy. However it will still be fairly inwards-looking, concentrated on domestic priorities, and thus will not be the hegemon that many fear. As it becomes richer throughout the century it will gradually become more free to dissent and responsive to citizens’ concerns, as South Korea and Taiwan did, though with less freewheeling democracy than Western nations. Speaking of Taiwan, it will likely be reunified with the mainland, which will be a less contentious process as the two models of government become more similar.
South and southeast Asia will experience rapid growth midcentury, due to basically the same factors that propelled East Asia: a cheap and highly educated workforce. India and ASEAN will be important.
The Middle East: I don’t feel confident making century-long predictions here, but I don’t think the situation will improve for the next several decades. The UN will not have the will to prevent Iran from obtaining nukes. Whether they are actually used or simply used as a means to get more diplomatic clout I can’t say. Israel will continue to exist and flourish as long as nukes don’t enter the equation - they have the will to defend themselves and the protestations of the EU will have less and less influence.
Africa: I see at least one or two success stories happening here, but they will be isolated and not general. There will be big differences between rich and poor, and likely conflicts between rich and poor nations (for plunder, or for expelling the inevitable wave of immigrants).
The EU: will expand and largely absorb old nationalities at least to the point of the US at its founding. Immigration will continue, and the wealthy will downplay its attendant problems. (Exception: Scandinavia will at least attempt to restrict immigration as Denmark has started to do.) Eventually anti-immigration groups emerge, but will be weak, comprised of the lower class that can’t afford to insulate itself from street crime etc. These will fail. In the optimistic scenario Muslims will begin to act like Westerners once they become more wealthy, and the sense of a separate identity will cease. Either way, Europe will continue on its trajectory of being relatively wealthy but undynamic (maybe sliding down to “middle-income” by century’s end), notable largely for its preservation of traditional high culture.
South America: Unremarkable but steady growth, several countries will become first-world nations by the end of the century.
Russia: the wildcard. It will continue to be a rival of the EU for influence over the “near abroad,” with occasional military actions like its incursion into Georgia. However it’s in economic and demographic decline, and this posturing will become more precarious as time goes on. Whether this scenario ends with a bang or a whimper is one of the most important questions for the next century.
One cultural prediction: as Christianity continues to decline in the Western world, various quasi-religious beliefs (“spirituality”) have sprung up in its place. Evidently religion is a primal need for many people. Eventually these weak strands of quasi-religion will accrete to form a new syncretic religion, which will become a major force among the middle and upper classes and cultural elite. This religion is likely to be easygoing and undogmatic, making few moral claims, but will have a more coherent theology than the current “spiritual but not religious” crowd, likely informed by Gaianism and animism. Christianity will become a religion of the lower classes in the West, though it may gain adherents elsewhere, especially in Asia.
