In many cases the former president, Nyerere, hasn't been taken down.
Obama pops up in various forms all the time as a constant reminder of the fact that there is more to life.
I just read his recent speech from Cairo here, which filled me with hope. I know that the rest of the world is working overtime to analyse what the speech really will mean.
Sometimes things are what they are, and should just be kept simple.
Like when expressed on a kanga.