Bitcoin won't ever become a world currency. Go look at places below or at the poverty line. They can't afford to own a Bitcoin wallet or have access to one.
I beg (no pun intended) to differ, even in places like kenya people like poor farmers are doing bitcoin transactions using SMS services on old (non-smart) 2g phones! ( CoinPip ) And yes ok, not all the world has a phone, but that too is changing very fast.
Sorry Howard. i'm from Kenya and I can confirm that this is false. Farmers don't even know Bitcoin exist. Maybe Old white oligarch farmers with huge tracts of land and of European descent.
Thanks for the insight. You have heard of m-pesa though right?? pretty ubiquotous in Kenya, well the bitcoin derivative bitPesa is taking it's place
http://www.ihavebitcoins.com/featured/kenyan-farmer-may-start-using-bitcoin/May be a work in progress, so would be interesting to see what actual contact you have with bitPesa over there. btw, Kenya was my all time favourite holiday destination in the 60's used to go to Silversands, Whispering Palms & Mombassa.