That is a fact or at least the US will try to keep it "officially on" as with Korea.
Absolutely correct. I definitely do not want to go into a very long dissertation on the subject but the short of is that the US never really wanted to "win" in Vietnam or maybe I ought to say that "winning" was an impossible dream anyway so the US did the next best thing by prolonging the gazillions of dollar influx supplied by tax dollars to fund the Military-Industrial Complex of perpetual war. What you just said above is the shortest version of the same thing.
No, I don't think so.
Castro succeeded in kicking out the American mafia but Cuba is still suffering the consequences of standing up to the big boys mainly because no one really understood that the US is a mafia-like organization.
Mossadeq's democracy got the rug pulled out from under it by the CIA. Ayatollah Khomeini got his revenge but once again the pain of standing up to the big boys is a perpetual fact. They really got the shaft going from Democracy to American-backed Fascism and then on to Islamic-backed Fascism.
I think the best we can hope for is for Europe (one by one) to get the US out of the continent, dismantle NATO, and reform the UN. There's much more work to do than that but that's the groundwork that's needed before anything else can be done.