In the world today, there is a lot of conflict going on, but it often seems to people living in the rich, comfortable West that wars are things that happen to the poor and downtrodden in other areas. But then, major wars of the 20th century aren't so far in the past - could the big players in those wars, the richest nations in the world today, end up at arms with each other again? How? When? What will our descendents be playing in their wargames? Here is a poll for you to express your opinion on how likely a war like this might be.
If you need some helping sorting out nations by GDP, there's a variety of convenient lists on Wikipedia;
Speculating about the next 25 years? Useful, some potential conflicts could be identified.
The next 50 years? Very hard to tell. Major changes to the international system can happen within that time frame, radically raising or decreasing the odds of another major interstate war. From the vantage point of 1815, for example, it might have looked as though the next 50 years after putting down the Napoleonic ogre would be relatively peaceful. That prediction would have been slightly wrong, given conflicts like the Crimean War. Looking past the 50 year mark, it would have been really, really wrong.
Beyond 50 years? We have no basis for prediction at all. Maybe some "grand historic" changes, such as economic globalization, might affect the odds of war. But in which direction?
The questions that cover the next 25 years seem interesting, but has there ever been a 50 year period without "Top 30 by GDP versus another top 30 by GDP"? All the questions after that seem to border on a near certainty.
Next 30 includes Angola, Pakistan, Israel, Iran, Kuwait, Egypt, Colombia, UAR, etc. Iraq, Libya, Croatia, etc. are almost there also. One more tick in oil prices would probably bring Iraq and Libya into the "next 30". Given that a lot of these states have warred within the last 50 years, and that almost everyone has warred within the last 100, it's not hard for me to imagine it happening again.
"If everybody is thinking alike, then somebody isn't thinking."
I'm not smart enough to decipher this poll but I think you might consider another element -- the fracture of a major power into smaller political units.
The United States and/or Russia could experience a crisis that results in a split into Balkanized homelands. If China remains stable or grows stronger that nation could be a superpower in a world of minor players. A coalition of Islamic nations (probably highly unstable and quite temporary) could be possible. The futuristic wargame player in me wants to see Brazil and/or India become major military powers.
To answer your question... the old power alignments might shift with new, regional powers grinding together at military flashpoints. I'll probably be dead and gone in 25 years, so I won't be around to play the wargame. That's OK. I'll be content with the current selection of hypothetical scenarios.
I'd hate to speculate. Ultimately I think we're far too interconnected now both by ethnic and financial dispersement throughout the world. It seems unlikely that such dissimilar groups with so much to lose would resort to something broader than what we've seen over the last 20 years (Balkans through today).
Clearly, most nations in the top 30 GDP aren't planning to go to war with other nations in that group in the immediate future. I agree that it is very hard to understand how the situation could be different in 200 years - that's a lot of time and we could all be living in the matrix by then or something.
So, a modified question then; what is a reasonable amount of time for both relations to shift such that war is feasible and yet it is not so far out from today that all bets are completely off?
Or is there no such point?
Maybe this gets a little sci-fi, but suppose there was a meteor impact and we had a hyper-winter; would something like that drive nations to war? Global climate change? It seems likely to me that we'll invent our way around an oil shortage - too many other ways to make electricity and store it - but I suppose that's possible.
Clearly, most nations in the top 30 GDP aren't planning to go to war with other nations in that group in the immediate future.
Yet there was some real concern both among Polish politicians and ordinary citizens after Russia invaded Georgia and was saber-rattling against Poland accepting a US missile base, and then a top Russian General was talking about how Russia should attack Poland.
I'm afraid to say I would not be utterly amazed if something like that happened within the next 25 years.
"I play to win, as much or more than any egoist who thinks he's going to win by other means. I want to win the match. But I don't give in to tactical reasoning as the only way to win, rather I believe that efficacy is not divorced from beauty."
India Vs. Pakistan will go to war within the next 25 years over a scarce resource, controlled by one, lifeblood of the other;
The Indus river rises in India, and flows to Pakistan where it feeds the largest contiguous area of agricultural land in the world. It is the main artery of Pakistan.
Helpfully, India and Pakistan have a treaty, dating from partition, which says India can take a fixed volume from the river yearly.
A river that is fed entirely by snowmelt from the Himalyas, and which is decreasing in annual volume yearly.
I'd give it 15 years before this goes off. Less if Pakistan crumbles apart.