100 years ago the British Empire ruled the world, now it's a small island you don't hear much about... The US is only about 250 years old, I'd be cautious about predicting the future

~1920 is the peak of the British Empire in term of territory, anyways, the details are meaningless, what matters is that things move fast and just because you're at the top of your game right now doesn't mean you'll be in the same position in 100 years

I could also take the example of world wars, in France ww1 was deemed "la der des ders", which meant "the very last war" or "the war to end all wars", well 20 years later we were at it again

Or simply look at China, you don't even have to go back 100 years in the past to see drastic changes.

That's only the case if you include Canada and Australia, which were functionally independent at that point.

I'm not claiming nobody will invade France or Taiwan in the next 100 years, I'm claiming that the US is special. We haven't been invaded since 1812 and haven't really been attacked since 1941. It's reasonable to predict we won't be invaded or go to war with our neighbors for 100 years since it hasn't happened for 213 years

This strikes me as hubris in the extreme.

My own death has not yet been a problem for me, but I can safely assume it will be.

Because everyone dies. If everyone lived to be 1000 you'd be wrong to worry about dying in 100 years

Surely based on history the odds of a conflict between neighbouring countries increases with time passed.

No, based on the history of conflict we can say that the more time that passes with neighbors not invading one another, the less likely they will in the future

It sounds like you’re making the assumption that things will remain static because the alternative is unfathomable to even consider.

100 years? Only a fool would attempt that. 100 years from now Uzbekistan could be fighting Brazil in orbit around Venus.

Definitely non-zero. If you were Mexican or Canadian you would not take the bet on even 20 years right now so who would bet on 100?

If we include the idea that either one of them is allied to a major power at war with the US over a hundred year horizon, right now that looks pretty likely, and arguably is one of the things the current US admin are trying to stop before it becomes inevitable.

The US admin is very clearly pushing us in the opposite direction. You believe that Trump's actions make war with Canada less likely? What's the mechanistic explanation?

Didn't the US join 2 world wars it did not start (or was involved in starting) in the last ~100 years?

Not against our neighbors

If the US didn't enter WW2, we would have new neighbors. The technology has made the world a small neighborhood.

So the argument is that the neighbors will never ally and be involved in a war that puts US on the opposite side? What is the argument for the sovereign neighbors to always be neutral or on US side come what may?

Yes, that's right. This has been the case for over 200 years so I think it's reasonable it will continue to be true for at least another 100

Germany was trying to get Mexico to join them for wwi, with enticement of getting back the land they lost 70 years prior. That loss was immense for Mexico in land, pride, and economics

Mexico was dealing with its own internal issues (revolution) which made it difficult for them

A slight turn of events and the us would have a huge southern front I deal with, and a base of support for disaffected native Americans and African Americans.

Russia also dropped out of Wwi due to its intern revolution

It is easy to look back and see manifest destiny as a given. There were a lot of contingencies

The fact that they're much smaller than the US and right there. Both would have their key cities flattened within 30 days.

Mexican warlords (which we colloquially call "cartels") are fighting a small war with the US right now and have been for many years.

What does that mean? No they aren't? When is the last time cartels attacked the American military?

You understand that for basically every violent entity in the world (except China and Russia), avoiding the US Mil is their best path to success and continued survival?

"War" as a concept does not have to include two militaries fighting each other.

If the cartels are waging a war against the US, so is a large number of American oligarchs. When will they start being on the receiving end of drone strikes and special operations?

When you stretch the definition of war to absurdity, so can I.