I am going to try something I have not done in a while, and actually answer your questions and not just put out snappy one liners, cause I can't think of any. It has never worked in it past, but what the hell right?
You think we will all march happily ever after into the future?
No, I assume we will go into the future like a new born baby. Crying and screaming and wetting ourselves, but over the years I expect us to calm down a bit (or kill ourselves.)
I don't think the difference between rich and poor under the society and economical structure we are now will be resolve in centuries.
What you describe here is not everyone content and happy. What you describe is not the hypothetical end of progress. Basically you are saying since when A is true B is true, thus B must ALWAYS be true... Which is it not if A is false.
And the difference between countries/cultures will not magically disappear either.
I am sure they will persist long past their use, but if there is no cause of friction between them then, surprise surprise there is no friction between them. Once again it goes back to why would there be wars?
And we are just the luck few lived in a wealthy society compare to more than 2/3 of the rest.
Once again you make the mistake of using parts of the currant situation to support your theories in a totally different situation, if everyone is happy and content then THERE WOULD NOT BE A SPLIT LIKE THAT.
And it's the difference and those don't want to follow the rule will bring out the war.
See pretty much every point.
Lack of variety has proven to be disasters in history and in evolution. Who do you think that we are the only living beings in the Universe? Simply because we can't see them, don't mean the competition don't exist. Hell, it might even being one of the sub-species of human after genetic modifications, or simply by pure mutation. A specie fail to adapt the changes will be eliminated.
Okay, even if some aliens come out of no where all of a sudden. I at least find it much more likely they will not be hostile, although of course it is very hard to tell cause we know nothing about them right now.
Argument:Assuredly a it will come down to whomever has the highest tech levels, after all, numbers don't really count for anything, you know who wins between 20 guys charging at one guy with a machine gun? The guy with the machine gun. Thus they would only be a threat if they had a higher technology then us, and thus they would be able to support themselves in luxury as we would, taking away any reason to attack us. Now, the only exception is if they have some racial psycho shit going down, and then I find it more logical that any race like that would be unable to reach the required amount of cooperation, after all, humans can't advance anything with the help of other humans, and I fail to see why that would be different for other species.