Based on what Monte is saying, I think its safe to say that Essentials is a sort of 5e preview, at least in terms of concept.
So you have an Essentials Fighter which is very simple. No dailies, one simple encounter attack power and some encounter utilities. That's it. The 5e version could be even simpler.
Now you have the 4e PHB Fighter with all its build options from the core PHB plus Martial Power. It has multiple at-wills, encounters, and dailies to choose from. Its very customizable.
Both fighters co-exist quite elegantly in the same game. I know, because I have DMed for both in the same game. The PHB fighter has a better ability to spike with their dailies and in certain situations where they happen to have the perfect power to use, but overall the Essentials fighter is rock steady and consistently on par but without the hills and valleys of the PHB fighter. Mathematically both are balanced and neither one outshines the other. One is just more customizable with more options to choose from.
I could see this in 5e and I think it would be awesome!
You have your core 5e fighter which would play and feel very similarly to a 1e fighter. But you could dig into the options book and really go to town with options if you want.