Between automation of our manufacturing processes, and huge population growths among the poorer nations and depressed ethnic groups, this "income inequality" is certain to continue to increase...until all Hell breaks loose. We see it here in the disparity between our mainstream population and the poverty that persists in our minorities. Europe is heading for troubles with the influx of immigrants flowing in from Africa and the Middle East. The availability of good paying jobs continues to decrease, while the number of unskilled people continues to grow. This is a sure recipe for disaster.
I remember reading a report way back in the 1960's about the future of humanity. There was a gathering of Academics and Futurists in Switzerland, and they speculated on the future of humanity. Their conclusion was that sometime in the latter half of the 21st century, there would be one more massive World War. This would Not be a war between nations, but rather a global conflict between the Have's and Have Not's. It would basically boil down to either the Have's running out of bullets, or the Have Not's running out of bodies. If the Have's win, humanity comes together under one Global government and reaches for the stars. If the Have Not's win, we revert back to the Middle Ages.
It seems that with every passing year, there is mounting evidence that these "predictions" may be coming true.