Humans are smart. They are able to solve problems. If an ocean forms in Africa, humans will find other places to live, or they will figure out how to live in the ocean. Humans discovered crude oil and they have lived on it for 100 years. They will come up with new technology.
No, no humans will be alive for the ocean that some scientists say is forming in Africa because we are working too quickly to destroy ourselves. We elect leaders who do not have our interests at heart, and we will not be able to survive if we do not change the way we treat the world.
In terms of the total existence of planet Earth it is expected that homo sapiens will only exist for a small percentage of it. We will become extinct in the near future, in percentage terms at least. Because of this I don't expect any humans to see the ocean forming in Africa. Whether we die out because of natural causes or man made situations cause the end I don't know, but I think it will be before a new ocean forms.
I find it highly unlikely that humans will survive another hundred years, never mind hundreds of thousands of years. Climate change, nuclear weapons, terrorism and sheer overpopulation will cause our human race to cave in on itself. It seems very negative but, unfortunately, destruction seems to be in our near future.