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I don't think Africa would have developed to our level of technology because of the general lack of iron and coal deposits in proximity.
The lack would mean no steam power, no steam power means no industrialization, no industrialization means no decent technology, no computerization, no mathematics, etc.
Coal deposits are found in South Africa and iron is found mostly in the west-sub-Saharan region (the bulging part).
Even before that, there were no horses, which meant no manner of traversing easy distances, which has all kinds of infrastructural implications as well as agricultural malus.
The lack of writing was also a big problem, since you depend totally on oral tradition, which gets distorted over the generations. It also means your education is going to be pretty limited, which we all know how it affects a person's IQ.
China, for example, never developed transparent glass for some strange reason, so they never got eyeglasses, which deprived scholars 10-20 years of work, which when added up means quite a lot. Such an inventive people as the Chinese (with also such a huge population), yet they never had glass, never saw the need for it either, it seems.
So if by some manner, Africans could develop all that, perhaps in a couple of centuries or millenia, they would have, there was nothing stopping them.
But if left alone, they wouldn't have developed it by 2015, because most didn't have writing to begin with in the early 1800s. Let's say a genius African develops a system of writing in the year 2000 and teaches it to his confederation of tribes, and another African tames the zebra. Judging by how Eurasian civilization developed (Starting with the Sumerians developing writing at around 3200BC), we can assume that Africans would have, more or less, developed our society (unless they ran into a scientific dead-end like the Chinese did, due to a deficit in mineral deposits, or some other unfathomable reason), by the year 7200AD, give or take a millenium.
For example, Mesoamericans developed writing around 600BC, and they were pretty much at the level of technology the Roman Empire had by the time Colombus made it there.
So in my opinion, what matters is the time at which that bright spark flashes in a tribesman's mind to perform the first great intellectual leap: writing. After that, it's basically a rollercoaster.