The US will come to talk to us when they have a black president and the world has a Latin American Pope. - Fidel Castro 1973
I've also seen it on twitter,
All references about this quote are recent in Internet (after Latin-american Pope and black president facts). It can be found using Google's date range. So it's very likely that these statements were invented. The trusted link about this story is in Clarin, a big newspaper in Argentina. The original source is from a small newspaper in Argentina at March,10,2015. An English journalist "Bryan Davis" is the alleged asker. No information about him can be found.
This source has already researched this answer. They claim, and cite, the original quote being
“Estados Unidos vendrá a dialogar con nosotros cuando tenga un Presidente negro y haya en el mundo un Papa latinoamericano”.
Which would make the quote correct. They conclude that context as a prophecy is incorrect because Fidel was referring to the embargo ending not merely Cuba talking to the USA. And, further, that even if the embargo ended it wouldn't be because of the "anti-bourgeois position of the president and the Pope".
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