MHL moves 1080p24 video and 8-channel audio over a micro-USB connector. The use cases for the 'dock port' in 2012 are docking in cars/alarm clocks/speakers/video docks and charging. MHL covers the first set, and any charger can give the right amount of amperage as long as they reverse-engineer Apple's hacky way of using a resistor grid on the data pins to control how much power the device can take.
Just because you don't hear about these things in the Magical Revolutionary Wonderful Apple bubble doesn't mean they don't exist. MHL to HDMI cables exist today and are usable today.