I am no expert but I think that a microcontroller and a microprocessor are 2 types or components with 2 different requirements. Like in a car, you have a transmission and a motor. 2 different components that make a whole. Right now with the beagle bone black and soon to be Tre We a have a Linux operating system that is currently geared towards traditional computing using a keyboard mouse and display. Basically a glorified word processor. However this opens up new possibility to the micro controller world. Really looking forward to the Arduino TRE.
A classic example is with Android. Based on linux, a smart phone is offering a lot of feature and I would not be surprise that Android could jump in. In fact it as already started.