the 5D3 does have a dedicated AF processor, like the 7D and the 1Dx. thats why these cameras have superior AF.
the 70D indeed has at least one dedicated AF processor... for CMOS AF.
check the interview here: http://www.learn.usa.canon.com/resources/articles/2013/eos_70d_interview_with_developers.shtml, page 4, top of right column.
Miyanari: “With the AF signal of Dual Pixel CMOS AF, there was twice the amount of information as the number of effective pixels that lined the sensor. This process could be performed with just the imaging processor; however, we believed it would be too much to ask, so a dedicated IC was developed. By establishing an IC for the role of preparation so the imaging processor could process one after the other, high-speed, optimized processing was made possible."
so, the digic 5+ is capable of handling such that computing capacity, I don't think that a separate AF processor should be used, but if they use one for CMOS AF, they might applied the other for the conventional AF.